The Invasion of Grenada

On October 25, 1983, the United States invaded the tiny Caribbean nation of Grenada ("Operation Urgent Fury").  The 1,500-strong Grenadian Army, along with 600 Cuban allies, were considered such a strategic threat to the Imperial Power that Ronnie Reagan sent in the Marines, lying through his teeth to his erstwhile ally Margaret Thatcher all the while.

Lest we forget:  opposition to the power will be crushed ruthlessly no matter how petty it makes the power look.