Trireme

Introduced in Warlords Naval Unit
Strength	2
Moves	2
Cost	50
Upgrades to	Caravel or Frigate
Required technologies	Metal Casting, Sailing
Required resources	N/A
Other attributes	+50% vs. Galleys Cannot enter ocean

The trireme is one of the first warships available in Civilization 4. It is used primarily to attack or defend Galleys. It can be upgraded to a Caravel if Astronomy is researched, or a Frigate if Chemistry is researched.