In The Warlord of the Air the Great Powers were
- Great Britain and the British Empire
- the Greater American Commonwealth - an empire in all but name, it comprises the Continental US, Cuba, Panama, Hawaii, the Philippines, Vietnam, Korea and Taiwan
Ranged against them were
In The Land Leviathan the Great Powers were
In The Steel Tsar the British Empire is larger than in Oswald Bastable's own world, holding parts of mainland North and South America. France is no longer a Great Power after failing to recover from the Franco-Prussian wars. Germany controls much of the old French Empire and is a close ally of Britain. The Ottoman Empire had expanded into Africa and the Middle East. The Japanese Empire controlled much of what had been China. Russia's empire stretched into eastern Europe.