Last week was the Copacabana Fort Revolt's centennial. That's misleading, it was actually a large failed coup d'état, with the Copacabana Fort as one of the few successful uprisings.

The coup plotters were mostly officers, all of them feeling the military's honor had been tarnished and refusing to accept the presidential election's results. Elections were all blatantly unfair in that period. They conspired unprofessionally for months and the government reacted well in advance, transferring unreliable commanders away from the capital. All the plotters had left was a handful of commanders and a number of rash younger officers, with old marshal and former President Hermes da Fonseca as their figurehead.

They were set to overthrow the government on the 5th of July, 1922, by taking over the main garrison in the capital, the Vila Militar. Led by Hermes, a column would follow the main railway towards the Army HQ on the city center, engaging legalists on their way. With the legalists distracted, a detachment would snake around and reach the presidential palace (Catete) from the "rear". They'd have solid fire support from Guanabara Bay's coastal artillery.

As the conspiracy was sloppily organized, the government pre-empted the plotters on the 4th of July and by nighttime had deployed patrols and arrested most of the rebellious officers before they could even act. A legalist general entered Copacabana Fort without an escort and tried to assume control, but he was arrested by the commander, who was one of the rebels. After midnight, the 7th Company of the 1st Infantry Regiment rose up, tried to arrest the garrison's commanders and was quickly contained. ~500 cadets and instructors at the Realengo Military Academy, where all officers came from, headed to the Vila Militar expecting fellow rebels and were met with gunfire. They took to the hills north of the garrison and engaged in combat with the thousands-strong legalist force for most of the morning before giving up.