Capturing enigma : how HMS Petard seized the German naval codes

An attack by a British destroyer on a German U-boat in the Eastern Mediterranean in October 1942 altered the course of the entire war.

The capture of secret coding material from U-559, at the cost of two of HMS Petard's crew, enabled Bletchley Park's codebreakers to successfully crack the U-boat cypher.

It was the crucial factor in defeating Hitler's Atlantic U-boat wolf packs before they succeeded in starving Britain into defeat in the winter of 1942-1943.

Here is the true story of how HMS Petard attacked and captured U-559 in the darkness of a Mediterranean night.

It describes how members of her crew swam across to the slowly sinking U-boat and captured vital German Enigma codebooks.

But the damage sustained by U-559 in the earlier attack proved fatal and without warning she sank before Petard could take her in tow.

Two of the destroyer's crew were trapped in the conning tower and went to the bottom with her.

Both men were later recommended for posthumous awards of the Victoria Cross but the Admiralty, concerned this might draw unwanted attention from German Intelligence, instead ordered posthumous awards of the George Cross, the highest civilian award for bravery.