In 1917, the war entered a new phase. Russia was shaken by revolution, first in February and then again in October, transforming the political map of Europe and weakening one of the Allies.

The United States entered the war in April 1917, giving the Allies growing economic and military support. On the Western Front, however, exhaustion was everywhere. The French Army experienced mutinies, and battles such as Passchendaele showed the terrible cost of continued offensives.

This year was marked by instability, uncertainty, and change. Old empires were weakening, new political forces were emerging, and the balance of the war was beginning to shift.

Key themes for 1917:

• The Russian Revolutions
• U.S. entry into the war
• French mutinies
• Passchendaele
• A major turning point in the conflict