| Just as in the First World War, U-boats nearly brought the UK to its knees. |
| German U-boats, sometimes assisted by Italian submarines, were the main weapon of attack, but aircraft and surface raiders also participated. |
| What if Germany's U-boats had won the Battle of the Atlantic and starved Britain into submission? |
| They recovered code-books and minefield plans from sunken German U-boats in World War One. |
| In 1940, the U-boats started to take a real toll against merchant shipping. |
| As bad luck would have it, nine German U-boats stumbled across the manoeuvres and torpedoed the ships, sinking two ships and damaging a third. |
