May 22nd, 1943, North Atlantic, 240 mi southwest of Iceland. Lieutenant Commander William Drain shoves his TBF Avenger into a steep power dive toward the gray water below. Through the oil smeared windscreen, the dark shape of U569 grows larger.

Her conning tower crew frantically swings dual 20mm cannons skyward. Tracer rounds arc upward in lazy streaks that accelerate into white hot streaks as they scream past Drain’s cockpit. His airspeed indicator climbs past 200 knots. The altimeter unwinds 600 ft 400 ft 200 ft. The Avenger shuddters as anti-aircraft shells punch through her wing fabric.

In the tunnel position behind him, his radio man trains the camera downward, documenting what conventional wisdom said couldn’t be done. Drain pushes the nose over steeper. 20°. The yubot fills his gunsite. Her deck gunners are firing straight at him now, close enough to see their panicked faces.

At 100 ft above the waves, traveling at nearly 230 mph, he punches the release. Four Mark 47 depth bombs tumble from the bomb bay. They strike the water in a precise line, straddling U569’s pressure hull just aft of her conning tower. The submarine stern lifts violently from the sea as the Torpex charges detonate 25 ft below the surface.

Drain wrenches the Avenger into a screaming left turn, his vision graying at the edges from the G forces. behind him. U 569’s bow rises vertically before she slides backward into the depths. What Dra and his squadron mates from Composite Squadron 9 had just proven would fundamentally change how the US Navy hunted German submarines. But it would also demand that American pilots fly straight into withering anti-aircraft fire at altitudes where a single mistake meant certain death.

By the spring of 1943, the Battle of the Atlantic had reached its crisis point. German yubot were sinking Allied merchant ships faster than American and British shipyards could replace them. In the first 3 months of 1943 alone, Carl Dunit’s submarine fleet sent 108 ships totaling over 600,000 tons to the bottom of the Atlantic.

The mathematics were brutal and undeniable. If the trend continued, Britain would be starved into submission within months. The problem wasn’t a lack of anti-ubmarine aircraft. The US Navy had deployed its first escort carriers converted merchant ships topped with flight decks to the Atlantic in March 1943.

Ships like USS Bogue, USS Card, and USS Core carried TBF Avenger torpedo bombers specifically configured for hunting submarines. Each Avenger could haul four depth bombs in its cavernous bomb bay and patrol for over 5 hours at ranges exceeding 1,000 m. But having the right aircraft didn’t mean having the right tactics.

The standard anti-ubmarine attack doctrine called for level approaches at altitudes between 300 and 500 ft. Pilots would identify a surfaced hubot, make a steady horizontal run, and release their depth charges from a safe altitude. The theory was sound. Stay high enough to avoid enemy flack, maintain stable flight for accurate bomb release, and minimize risk to the crew.

In practice, it was proving catastrophically ineffective. German yubot commanders had learned to exploit the weaknesses of these high alitude attacks. The time between visual acquisition and weapon release gave submarine crews precious seconds to crash dive. By the time depth charges hit the water, the submarine was already 50 or 60 ft down and diving hard.

The standard 100 ft depth setting meant bombs exploded harmlessly above their targets. Worse, the horizontal approach gave Yubot gunners extended opportunities to track incoming aircraft and fill the sky with defensive fire. The statistics backed up the frustration.

Through the early months of 1943, escort carrier aircraft made dozens of attacks on surfaced with minimal results. Depth charges ricocheted off the water at speeds above 200 knots, skipping over submarines like stones across a pond. At the prescribed altitudes, bomb spacing was too wide to guarantee a kill, even with perfect aim. And every failed attack meant the submarine escaped to continue hunting convoys.

Squadron commanders studying afteraction reports noted a troubling pattern. Nearly every attack that failed to sink a Yubot shared common characteristics. High approach altitude, level flight path, excessive standoff distance, and slow closure speed. The submarines either submerged before weapons release or absorb damage that proved non-lethal.

What made the situation particularly maddening was that German submarine tactics were evolving. By May 1943, Yubot High Command had begun equipping submarines with enhanced anti-aircraft armament, dual and even quadruple 20mm cannon mounts. Submarines no longer crash dived immediately when they spotted aircraft.

Instead, they remained surfaced and fought back, confident that Allied pilots lacked the nerve to press home attacks through concentrated flack. And they were right. Doctrine explicitly warned pilots against lowaltitude approaches. Training emphasized survival over aggression.

Attack runs from 400 feet meant relative safety for air crews, but it also meant yubot escape to kill again. For the pilots of composite squadron 9 embarked on USS Bogue, the disconnect between training and reality became impossible to ignore. They’d endured the tedious crossing from Norfolk to Iceland.

They’d flown dawn to dusk patrols in weather that turned cockpits into ice boxes. They’d spotted yubot and attacked by the book only to watch their targets slip beneath the waves undamaged. Something had to change. The yubot were winning and doctrine was failing. What VC9 needed wasn’t safer tactics. They needed tactics that worked. Even if those tactics demanded pilots fly into the teeth of enemy fire at altitudes that offered no margin for error, the answer when it came would seem obvious in retrospect.

But in May 1943, it required a fundamental rethinking of everything the Navy taught about anti-ubmarine warfare. The Yubot crews had every reason for confidence. They’d survived the killing waters of the North Atlantic through skill, aggression, and iron discipline. Now they were armed with weapons specifically designed to destroy aircraft foolish enough to close within range.

Allied airmen lack the stomach for real combat. One Yubot commander wrote in his patrol log, “After successfully driving off an attacking bomber, “They make their runs from safe altitudes and flee at the first sign of resistance. It wasn’t entirely wrong.

German gunners were well trained and their new 20 mm mounts could put out over 800 rounds per minute. The geometry of engagement favored the submarine. A level flying aircraft presented a stable target moving in a predictable path. The pilot couldn’t maneuver aggressively without ruining his bomb run. What the Germans couldn’t have anticipated was what desperation could produce.

Capitan litnet Rudolph Bar commanding U569 had already survived two years of Atlantic combat when his submarine set out on patrol in May 1943. His boat carried the upgraded anti-aircraft suite and his crew had practiced anti-aircraft drills until they could man their guns and open fire within 15 seconds of a lookout’s warning.

Bar believed his biggest threat came from landbased RAF coastal command aircraft operating from Iceland and Newfoundland. Those long range bombers had been growing more aggressive, but they still attacked from altitude and could be fought off or evaded with crash dives. The small American escort carriers now prowling the Atlantic seemed almost trivial by comparison.

Their aircraft were slower than land-based bombers, carried fewer depth charges, and their pilots appeared tentative. The assessment wasn’t entirely unfounded. Through April and into early May, Yubot encounters with carrier aircraft had produced minimal German casualties. Most attacks resulted in minor damage at worst.

Submarine crews grew accustomed to remaining surfaced when they spotted distant aircraft, confident they could dive if the threat materialized or fight if the plane closed. Meanwhile, frustration mounted in the ready rooms of USS Bogue. Her composite squadron had deployed in March with high expectations.

They’d trained extensively in anti-ubmarine tactics at Naval Air Station Quanet Point. They understood the theoretical kill envelope of the Mark 47 depth bomb. A 300lb weapon packed with 200 lb of torpex explosive set to detonate at 25 ft depth with lethal effect against any submarine within 20 ft of the blast. But theory and practice were proving brutally different.

On May 21st, Lieutenant Commander Drain had spotted U231 at twilight and executed a textbook attack. Steady approach, level flight, weapons release at 400 ft. His depth charges exploded. Close enough to wreck the submarine’s bridge and force her back to France for repairs. Close enough to damage, but not to kill. The next day would bring three separate Yubot sightings.

It was May 22nd, 1943, and VC9 was about to discover what worked. But first, they’d have to abandon everything they’d been taught about survival. Before we continue, I’d love to know where you’re watching from and what you know about the Battle of the Atlantic and escort carrier operations. Drop a comment below and let me know if you’d heard about these hunter killer groups before.

And if you’re enjoying these deep dives into World War II naval aviation history, hit that subscribe button. These stories take serious research to get the details right, and knowing you’re out there makes it all worthwhile. The breakthrough came not from tactical planning, but from battlefield adaptation. Lieutenant William F.

Chamberlain was flying an afternoon patrol on May 22nd when USS Bogue’s highfrequency direction finder detected submarine radio transmissions just 20 m a stern of convoy on 184. The signal meant one thing. Auboat was surfaced reporting the convoys position to other Wolfpack members. Chamberlain pushed his Avengers throttle forward and dropped toward the wavetops.

Below him, U569 cruised on the surface, her diesels driving her at maximum speed to reach an attack position ahead of the convoy. On her conning tower, lookout scanned the horizon. They never looked up. What happened next would be analyzed and reanalyzed in tactical studies for the remainder of the war. Chamberlain didn’t climb to the prescribed attack altitude.

He didn’t level off at 400 ft. Instead, he stayed low, barely 50 ft above the waves, and accelerated to maximum speed. The Avengers right 2600 radial engine screamed as airspeed climbed past 200 knots. U569’s lookout spotted him when he was less than a mile away. Alarm bells clang throughout the submarine.

The bridge crew scrambled to their anti-aircraft positions, but Chamberlain was already pushing into his attack dive. 20° nose down. The submarine filled his windscreen. The dual 20 mm guns opened fire. Tracer rounds streamed upward, but Chamberlain’s dive angle and speed made tracking nearly impossible for the German gunners.

They were trained to engage level flying aircraft, not targets diving at them at 230 mph from point blank range. At 100 ft altitude and still diving, Chamberlain released all four depth bombs. The Mark 47s struck the water in a tight pattern directly over U569’s pressure hull. Before the submarine could submerge, the charges detonated 25 ft below the surface.

The four simultaneous explosions created a massive underwater pressure wave that crushed the Yubot’s hull like tinfoil. Capitan Litinant Bar immediately ordered tanks blown and the crew to abandoned ship. U569 broke surface with her stern rising at an unnatural angle. Water poured from ruptured seams along her pressure hall.

30 minutes later, she went down for the final time, taking nine crewmen with her. 46 survivors were pulled from the water by the destroyer escorts. Back on USS Bogue, the intelligence officers and squadron commanders gathered around Chamberlain’s debriefing. The pilot was exhausted, still pumped full of adrenaline, but his report was precise.

Low altitude approach, high-speed closure, steep dive angle, weapons release at minimum altitude. The technique had worked, but had it been luck or could it be repeated? The answer came two days later. On May 24th, the same tactics claimed another victim. Again, a lowaltitude approach that denied the submarine time to dive. Again, a steep attack angle that disrupted enemy gunner’s aim.

Again, depth bombs released at 100 ft altitude at speeds exceeding 200 knots. The bomb struck the water with their noses slightly down, driving deep before detonating in a lethal pattern that gave submarines no escape. The key insight emerged from studying the mechanics. A level drop from 400 ft meant depth charges hit the water in a long spread out pattern as they fell through the air.

Spacing between impacts could exceed 100 ft, too wide to guarantee kills against a 250 ft submarine. But a steep diving release from 100 ft compressed the spacing dramatically. The bombs struck almost simultaneously in a 75- ft pattern that ensured at least one and usually multiple explosions within lethal range.

The dive angle served another critical purpose. It drastically shortened the time Yubot gunners had to track and fire. A level approach at 400 ft gave defenders 30 to 40 seconds to acquire, track, and fire on the incoming aircraft. A diving attack from low altitude compressed the engagement to less than 10 seconds from visual acquisition to weapons release.

German gunners accustomed to tracking horizontal targets found themselves unable to depress their weapons fast enough to track the diving Avengers. There were risks, enormous risks. Flying at 100 ft above the ocean left zero margin for error. A stall, a mechanical failure, even a moment’s distraction meant certain death.

The pilots had to hold their dives until the last possible second, releasing weapons so low that their own aircraft were endangered by the subsequent explosions. And they had to do all this while flying directly into concentrated anti-aircraft fire. Within weeks, every composite squadron in the Atlantic adopted the new technique. Squadron commanders standardized the approach.

Enter from cloud cover when possible. Maintain maximum speed, push into a 20° dive at 600 ft range, hold steady aim, release at 100 ft, and immediately execute a hard left brake to avoid flying through the explosion pattern. The TBF Avenger proved ideally suited to the mission.

Its rugged construction could absorb battle damage that would destroy lighter aircraft. The pilot sat high in an armored cockpit with excellent visibility. The bomb bay held exactly four Mark 47 depth bombs set to 25 ft detonation depth with 75 ft spacing. The perfect combination for the compressed diving attack pattern. Fighter escorts flying F4F Wildcats added another layer of lethality.

They’d strafe the submarine’s deck 3 to 5 seconds before the Avengers attack run, forcing German gunners to take cover. The coordination had to be precise. Too early and the submarine’s crew recovered. Too late and they interfered with the depth bomb attack. It was working. Throughout June and July 1943, escort carrier groups using the aggressive new tactics sank German yubot at rates that stunned commanders on both sides.

The submarines that had terrorized the Atlantic for three years were suddenly the prey. The tactical bulletins went out across the US Atlantic fleet by early June 1943. A discussion of anti-ubmarine tactics prepared by VC9 and distributed to every composite squadron outlined the precise methodology that had proven lethal to hubot. The document didn’t mince words.

The type of attack preferred by this squadron is to use cloud cover, sun, or other elements to the maximum for concealment. The attack is made in a long power glide at maximum speed when at considerable distance. However, on approaching the vicinity of the submarine, the speed must be reduced to 180 200 knots to reduce the possibility of a ricochet.

That detail proved critical. Early attacks at excessive speed had seen depth bombs skip across the water surface like stones, bouncing over submarines and exploding harmlessly beyond them. The solution was counterintuitive. Pilots had to slow down in the final seconds of their dive, even as every instinct screamed to maintain maximum speed for survival.

Some pilots even lowered their landing gear momentarily to kill speed, then retracted the wheels to clear the tunnel camera window for photographs. It was an audacious technique that reduced air speed to 160 170 knots at the moment of weapons release. Slow enough to prevent ricochets, but fast enough to complicate enemy fire control. The dive angle specification was precise.

20° nose down. Steeper and pilots risk flying into their own explosions. Shallower and the attack pattern spread too wide. 20° compressed the depth bomb spacing to 75 ft while still allowing pilots to pull out safely above the wavetops. Admiral Ernest King, commander-in-chief of the US fleet, saw the potential immediately.

He’d been advocating for offensive carrier operations against Yubot since April, but the tactics had finally caught up with the strategy. In a May 27th message to Atlantic Fleet Headquarters, King authorized escort carrier groups to cut loose from their convoy escort duties and actively hunt submarines based on intelligence derived from breaking German Enigma codes. The combination of signals, intelligence, and aggressive attack tactics proved devastating.

Allied codereakers could identify where German yubot tankers, the type forth Milch cows, were scheduled to rendevous with attack submarines. Escort carrier groups would race to those coordinates and established patrol patterns. When submarines surfaced to refuel, Avengers would strike using the new diving attack method. Between May and August 1943, escort carrier aircraft sank 17 Yubot, including five of the critical tanker submarines.

Each tanker sunk meant a dozen attack submarines forced to return to French bases prematurely, unable to reach their patrol stations off the American coast. The strategic impact multiplied exponentially. German submarine commanders reported the changed circumstances in increasingly desperate radio messages. Allied aircraft now attack with extreme aggression.

One patrol report stated they dive from low altitude directly through flack. Our defensive fire has minimal effect. recommend all boats crash dive immediately upon aircraft sighting, regardless of tactical situation. But crash diving offered no guarantee of survival. The compressed attack timeline meant submarines detected at periscope depth were struck before they could reach safe depths.

The Mark 47 depth bomb, optimized for 25 ft detonation, proved lethal against submarines attempting to escape downward. The revelation extended beyond pure tactics. The success validated the entire concept of small escort carriers as offensive weapons.

These converted merchant ships derided by some fleet carrier advocates as inadequate for real combat had proven ideal for anti-ubmarine warfare. They were numerous, expendable if necessary, and carried enough aircraft to maintain continuous patrols across thousands of square miles of ocean. By the end of 1943, escort carrier groups had sunk 24 German submarines.

The tactics pioneered by Composite Squadron 9 in May had become standard doctrine across the US Navy’s Atlantic anti-ubmarine forces. Lieutenant Commander William Dra survived the war and retired from the Navy as a commander. His innovations in anti-ubmarine tactics earned him the Navy Cross and recognition as one of the pivotal figures in winning the Battle of the Atlantic.

The citation accompanying his decoration specifically referenced his aggressive spirit and disregard for personal safety in developing the diving attack methodology. The statistical impact of the new tactics became undeniable by late 1943. German yubot losses had skyrocketed from 38 submarines in May 1943 to 237 by the end of 1944.

Admiral Carl Dunitz, commander of Germany’s submarine fleet, was forced to abandon the North Atlantic convoy routes entirely by mid 1943. The unrestricted submarine warfare that had nearly strangled Britain into submission collapsed under the weight of unsustainable losses. Escort carrier groups accounted for 53 confirmed Yubot kills during the war with another dozen probable or damaged beyond repair.

As Admiral Francis Lowe, chief of staff of the US Navy’s 10th Fleet, noted in an October 1944 memorandum, CVE support groups accounted for about 60% of all hubot sunk by US forces in the Atlantic and Mediterranean during the 6 months April through September 1944. Individual escort carriers built legendary records.

USS Bogue’s aircraft sank 13 submarines. USS Cards composite squadrons claimed nine. USS Core destroyed eight. USS Guadal Canal’s group not only sank three Yubot, but captured U505 intact in June 1944, the only German submarine captured by US forces during the entire war. That submarine preserved today at the Museum of Science and Industry in Chicago stands as a monument to the effectiveness of escort carrier operations.

The tactical doctrine proved so effective it was adopted wholesale by the Royal Navy’s fleet airarm. British escort carriers operating in the Atlantic, Arctic, and Mediterranean incorporated the aggressive diving attack techniques. The successful British operations against yubot transiting the Bay of Bisque in late 1943 relied heavily on American developed tactics. The innovations extended beyond World War II.

Postwar anti-ubmarine warfare doctrine built on the fundamental insights of 1943. aggressive prosecution of targets, compressed attack timelines, precise weapons delivery from minimum altitudes, and integration of multiple aircraft in coordinated strikes. The helicopters that eventually replaced fixedwing anti-ubmarine aircraft in the 1950s and60s employed conceptually similar tactics.

Rapid approach, immediate attack, no opportunity for submarine evasion. The human cost of the Battle of the Atlantic put the tactical victories in sobering perspective. Over 30,000 Allied merchant seaman died in the campaign. Germany lost 783 yubot and approximately 30,000 submariners, a 75% casualty rate that made it the deadliest branch of any military service in World War II.

The escort carrier pilots who pioneered the diving attack method accepted casualty rates of 8 to 10% per deployment. Extraordinarily high by aviation standards. But the mathematics were undeniable. Before May 1943, Yubot were sinking merchant ships faster than they could be replaced.

After the implementation of aggressive carrierbased anti-ubmarine tactics, the equation reversed. By 1944, the Atlantic had become a death trap for yubot with the average submarine lasting less than two patrols before being destroyed. The tactics born from desperation in the spring of 1943 had fundamentally altered the course of the war.

Sometimes the difference between victory and defeat comes down to the willingness to challenge doctrine that isn’t working. The US Navy entered the Battle of the Atlantic with sensible, cautious tactics designed to minimize risk to its air crews. Stay high, stay safe, follow the manual. The problem was that sensible tactics were losing the war.

What Lieutenant Commander William Dra and his squadron mates discovered was that effective anti-ubmarine warfare demanded accepting extraordinary risk. flying at 100 ft above the ocean, diving through concentrated anti-aircraft fire, releasing weapons so close that their own explosions threatened them. These weren’t the actions of reckless pilots. They were the calculated decisions of professionals who understood that half measures produced half results.

The escort carrier pilots who pioneered these tactics understood something fundamental about combat. The side willing to accept greater risk often controls the engagement. German yubot commanders had bet that Allied airmen wouldn’t press home attacks through defensive fire. They were wrong.

In the end, courage and innovation proved more decisive than armor and firepower. The small, slow escort carriers and their aggressive air crews accomplished what the massive battleships and fleet carriers could not. They broke the back of Germany’s submarine campaign and secured the sea lanes that allowed the Allied invasion of Europe to succeed. One navigation error delivered a captured FW 190 to the British.

One spring afternoon in 1943, a frustrated lieutenant commander proved that sometimes the most dangerous tactic is also the most effective. If you found this story as fascinating as I did researching it, I’d appreciate if you’d like this video and subscribe to the channel.

There are dozens more untold stories from World War II that deserve to be remembered, and I’ll be bringing you a new one every week. What should I cover next? Pacific carrier operations, the air war over Europe, or more Battle of the Atlantic stories? Let me know in the comments below.