[Kapitän Cremer]

In case a U-boat was disabled out in the Atlantic it was standard procedure to send out a resupply sub, also known as Milk Cow, to try and repair any damage. If the U-boat couldn't be repaired it would be destroyed by its own crew.

As always it was a race on both sides because the allies were keen on getting their hands on the german enigma code machine.

Have you ever seen the movie U-571. Although a bit over dramatized it does draw a good picture of the strugge of the Enigma.