Fire Ships are a class of ships available from the Classical Age to the Enlightenment Age. They explode on contact with enemy ships, dealing massive damage or even destroying enemy vessels. Fire ships are effective against Heavy Ships and Bombardment Ships, but usually get destroyed when encountering Light Ships. In the Industrial Age, Fire Ships are upgraded to and replaced by Submarines. Submarines no longer explode on impact and stay hidden from enemy sight unless a detector unit spots them. The Germans built Fire Ships and Submarines 33% faster and 25% cheaper.