George Washington Williams (October 16, 1849 – August 2, 1891) was a soldier in the American Civil War and in Mexico before becoming a Baptist minister, politician, lawyer, journalist, and writer on African-American history.

Shocked by the widespread brutal abuses and slavery imposed on the Congolese, he wrote an open letter to Leopold in 1890 about the suffering of the region's native inhabitants at the hands of the king's agents.

This letter, which subsequently popularized the term "crimes against humanity", was a catalyst for an international outcry against the regime running the Congo, which had caused millions of deaths.

During the American Civil War, Williams ran away to enlist at the age of 14 in the Union Army under an assumed name; he fought during the final battles.

[4] After the war, Williams went to Mexico, where he was among Americans who joined the Republican Army under the command of General Espinosa, fighting to overthrow Emperor Maximilian.

Williams was assigned to the 10th Cavalry "Buffalo Soldiers" in the Indian Territory, but was wounded in a lung in 1868 and was hospitalized until his discharge that year.

According to his biographer, historian John Hope Franklin, he offended his constituents by offering a bill that "threatened to deny members of a local African Methodist church the right to bury their dead in what was becoming an exclusive suburb" of the river city.

[4] In the last weeks of his administration, President Chester A. Arthur nominated Williams as "Minister Resident and Consul General" to Haiti and Santo Domingo in early 1885, but he was not confirmed, as he was not considered qualified.

[7] Grover Cleveland, the president elected in 1884, nominated Democrat John E. W. Thompson to the positions soon after taking office in 1885.

[9] Although he failed to gain entry as a delegate to an anti-slave trade conference in Brussels in the spring of 1890, he made other arrangements to visit the city and the continent.

[4] From Stanley Falls, Williams wrote "An Open Letter to His Serene Majesty Leopold II, King of the Belgians and Sovereign of the Independent State of Congo" on July 18, 1890.

[12] In this letter, he condemned the brutal and inhuman treatment of the Congolese at the hands of Europeans and Africans supervising them for the Congo Free State.

[12] The King and his supporters tried to discredit Williams, but he continued to speak out about the abuses in the Congo Free State, helping to generate actions in Belgium and the international community.