Why is "Address of the International Working Men's Association to Abraham Lincoln" trending?

Wikipedia Overview

"Address of the International Working Men's Association to Abraham Lincoln, President of the United States of America" is a letter written by Karl Marx between November 22 to 29, 1864 that was addressed to then–United States President Abraham Lincoln by United States Ambassador Charles Francis Adams Sr. The letter was written on behalf of the International Workingmen's Association (IWA), an international organization of socialists, communists, anarchists and trade unionists. In the letter, Marx congratulates Lincoln on his re-election victory in the 1864 United States presidential election and congratulates him and the Union for fighting against slavery in the United States. Adams Sr. conveyed Lincoln's response to the letter, in which Lincoln briefly thanked the IWA for their support of the Union. The response was addressed to Randal Cremer, an abolitionist and trade unionist, although the response was also delivered to Marx and his friends. The letter was among thousands of congratulatory letters received by Lincoln from abroad.