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:

• Russia is shaken by revolution
• The United States enters the war
• French army mutinies reveal deep exhaustion
• Passchendaele shows the continued cost of offensives
• Political instability grows across Europe
• The balance of the war begins to shift