On March 21, 1937 (Palm Sunday), a march was organized in Ponce, Puerto Rico, by the island's Nationalist Party. It was organized to commemorate the ending of slavery in Puerto Rico in 1873, and to protest the jailing by the U.S. government of Pedro Albizu Campos.
The peaceful march turned into a massacre as 200 heavily armed members of the US-controlled Insular Police opened fire. The horrific attack using machines guns, rifles and tear gas bombs, was carried out under orders of General Blanton Winship, Puerto Rico's US colonial ruler, and police chief Colonel Francis Riggs...a fellow best known for helping establish the dictatorship of Anastasio Somoza in Nicaragua.
Seventeen unarmed marchers were murdered and 235 wounded, including women and children. Hundreds more were jailed. The US Congress moved quickly to immunize Riggs and Winship from any charges.
It was the biggest massacre in Puerto Rican history. The following is a 19 second clip of that day of infamy.