An Analysis of the devastation
wrought by U-boats during World War Two.

A post-second world war analysis of U-boat activity records some 4409 attacks on shipping. Subsequent analysis of this information reveals the following details;

n.b an attack does not imply the use of a single torpedo or shell.

Description of incidents Numbers Tons. % of
total attacks
Ships Sunk 2919 14,232,747 66.2
Ships damaged beyond repair 32 193,748 0.7
Ships Taken as prize 5 10,018 0.1
Damaged 401* 2,707,398 9.1
"Missed", attacks on identified targets with no result 103   2.3
Attacks where details are unable to be verified 949   21.5

*Of the 401 ships damaged, 101 of them (708,712 tons), were later sunk.

In total the allies lost 14,436,513 tons of shipping to the U-boats, this represents 68% of all the shipping lost by the allies due to enemy action (total 21,194,00 tons, Churchill's History of the Second World War Vol 2).

Thus we can see from the above figures that the U-boat was a devastatingly effective weapon.

Analysis By Weapon Type.

Weapon used Total No
Attacks
Sunk Damaged
Beyond
Repair
Damaged
Torpedo 3521 2408 24 312
Torpedo & Gunfire 209 191 1 11
FAT Torpedo 60 22 1 13
GNAT Torpedo 259 49 5 18
LUT Torpedo 20 3 1 3
Gunfire 215 158 0 16
Gunfire & Ramming 4 3 0 0
Gunfire & Scuttling 7 6 0 1
Mines 94 66 0 27
Ramming 5 3 0 0
Scuttling 10 10 0 0

The most disappointing weapon would appear to be the acoustic homing torpedo (GNAT=German Navy Acoustic Torpedo, also known as the G7s, T5 and code named Zaunkönig) it had a sinking success rate of about 19%. This was heralded as the "destroyer buster", it should have been a very successful weapon, with the U-boat commander only having to fire it in the general direction of the intended target. It is likely that this low strike rate is due primarily to the effectiveness of the allied countermeasures, in particular the use of the British FOXER and Canadian CAT, these noise boxes were towed along behind ships when in the dangerous waters.

Attack analysis compilation: Malcolm Holley.