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DEFEAT OF THE U-BOATS 169

PACIFIC

OCEAN

ATLANTIC

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Caribbean

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Norwegian

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Jamaica REPUBLIC

Puerto Rico

Cape Verde

Islands

Canary

Islands

Madeira

Azores

BRITISH

GUIANA

PANAMA

GUATEMALA

COSTA RICA

NICARAGUA

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REICHSKOMMISSARIAT
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OPERATION DRUMBEAT JANUARY–JUNE 1942
Despite heavy commitments in other theaters,
Admiral Dönitz moved as many U-boats as he
could spare to the US east coast. There they found
rich pickings targeting unescorted merchantmen,
which were often silhouetted at night against the
brightly-lit shoreline. Far from home, the U-boats
relied on the support of Milchkuh (“Milk-cow”)
supply submarines for refueling and provisioning
with food and torpedoes.
1
BLACK MAY FOR THE U-BOATS MAY 1943
May 1943 was to prove decisive in the long naval
war of attrition. In that month alone 41 U-boats
were sunk, while Allied losses continued to shrink.
On May 23 Dönitz finally accepted the inevitable
and ordered the temporary withdrawal of all
submarines from the mid-Atlantic, concluding that
“the enemy, by means of new location devices ...
makes fighting impossible.”
4
MID-ATLANTIC BATTLEGROUND
JUNE 1942–MARCH 1943
As US air cover improved and merchant ships were
organized into convoys, the U-boat kill rate fell from
128 ships in the first quarter of 1942 to just 21 in the
second. Dönitz responded by shifting his focus to the
mid-Atlantic, where air cover was patchy. The results
were dramatic: between June 1942 and late March
1943 over 1,000 ships were sunk, the majority in the
sea-lanes between Greenland and the Azores.
2
▷ B-24 Liberator
Made by Consolidated Aircraft
in California, the Liberator bomber
was highly effective in attacks
against surfaced U-boats.
Aug 1943 Portugal’s
dictator Antonio Salazar
agrees to allow Allied
forces to use air and naval
bases on the Azores.
Mar 16–20, 1943 Nine
ships of Convoy SC-122
are sunk in the mid-Atlantic.
May 4–5, 1943 More
than 40 U-boats attack
Convoy ONS-5.
Twelve merchantmen
are sunk, but at a cost
of six submarines sunk
and seven damaged.
Oct 12–16, 1942 Two wolf
packs sink 18 of the 48 ships of
Convoy SC-104.
THE TURN OF THE TIDE MARCH–APRIL 1943
The Allies responded to the U-boat threat with
measures including improved depth charges and
airborne anti-submarine rockets, together with the
aircraft needed to deliver them—notably the B-24
Liberators. Liberator bases were established at RAF
St. Eval in England and in French Morocco. Improved
intelligence also proved crucial: while 215 Allied ships
were lost from February 1 to March 19, 1943, only 25
went down from March 20 to April 30. The area of
U-boat success in the Atlantic began to shrink.
3
US anti-submarine Liberator bases
US_168-169_Defeat_of_U-boats.indd 169 19/03/19 7:28 PM