False flags are an American tradition. They go way back. The Boston bombings appear the latest. More on that below.
Notable earlier false flags or incidents approximating them include:
In 1845, America lawlessly annexed Texas. It was Mexican territory. President James Polk deployed US troops. A future president led them. General Zachary Taylor paraded them along the disputed border.
In May 1846, Polk told cabinet officials that if Mexican forces retaliated, he'd ask Congress to declare war. He wanted it whether or not Mexico attacked. After an incident occurred, Polk told Congress: