The list of units
Bombers are not as versatile as fighters, but they have a larger operational range and greater bombardment power. They may be based in any city or aircraft carrier on the map.
A city needs oil in its Strategic Resource box to build a bomber.
The bombing of strategic targets from the air dates back to the beginning of World War I, when the Germans used zeppelins to bomb Paris and London. Because zeppelins proved to be extremely vulnerable, they were withdrawn from war in favor of airplanes. By the end of World War I planes were being designed specifically as bombers. The bomber's job is to carry bombs into enemy territory, normally beyond the range of artillery, and destroy targets of military and economic value. Bombers were often designed for specific missions, such as attacking ships, bombing vehicles and railroads, daylight precision bombing, and carpet-bombing.