Event

Japan Invades Manchuria

Japan's move into Manchuria signaled that interwar revisionism was no longer only diplomatic and that the League of Nations lacked the power to stop major aggression.

Status: draft
Event Kind: invasion
Date Precision: day
Date Display: 18 Sep 1931
Start Date: 18 Sep 1931
End Date: 18 Sep 1931

What happened

Following the Mukden Incident, Japanese forces moved into Manchuria and established effective control over the region, later consolidating it in the puppet state of Manchukuo.

Why it matters

Manchuria is a decisive early test of collective security. It showed that aggression could proceed despite international condemnation and helped normalize the collapse of the post-1919 order.

Notes

This works as the first major revisionist-expansion anchor in the timeline.