The fourth phase in the history of overseas empires encompassed two world wars and global economic depression.

Western Europe was profoundly shaken by the unexpectedly long, bloody conflict of 1914-18, fought on its own soil, that termi­nated a century of relatively peaceful relations among its major states.

The colonies, by this time closely linked to their metropoles’ economies, could not avoid being affected by these traumatic events. They found themselves on a roller coaster ride, their human and material resources alternately mobilized and demobi­lized, their people’s expectations for change raised and then disappointed. The ups and downs of the ride deserve attention even if the political consequences of this dizzying experience were delayed for the most part until yet another global crisis, World War II, set off the final contractionist phase.

Phase 4 was a period of equilibrium in two senses. First, the net territo­rial dimensions of empire changed little, for imperial losses and gains were to some extent self-canceling. Second, powerful forces worked to consolidate European rule and to undermine it, thereby countering or neutralizing each other. Phase 4 was connected to the phases preceding and following it: to phase 3 because Euro­peans were able to act on territorial claims made earlier, turning the governance of vast areas from ambitious aspiration to institutionalized practice; and to phase 5 through the powerful stimulus war and depression gave indigenous forces chal­lenging external rule. In this respect the equilibrium was unstable, a moment of apparent stasis at a time of transition between the rise and decline of European dominance.