Submarine

Submarines are ships capable of travelling while submerged underwater.

Submarines are used by the Confederate Navy and other navies during the Great War to raid enemy shipping and disrupt supplies. They are also called submersibles and fared considerably better than the Confederate surface fleet against the larger and more powerful United States Navy.

During the Second Great War all the major powers again used submarines and are used along with naval aviation to threaten capital ships.

When the Race invades Earth submarines are crucial since the lizards largely lack the means to destroy them underwater and they can be used to transport crucial supplies and personel between the resisting human powers. Submarines are used to transport plutonium seized from the Raced to the United States and foreign ministers to London for the Big Five conferences. American and German submarines carrying  atomic bomb destroy the cities of Miami, Rome, and Alexandria by sailing into the ports undetected and detonating the bomb aboard the ship.

After the war, the major powers develop nuclear submarines capable of carrying ballistic missles. The Germans use them to great effect in the 1965-66 war with the Race devastating North Africa, Arabia, and Australia. They are fully active by the armistace compelling the Race to accept terms less than unconditional surrender since the Germans can nuke their colonies further.