Abraham Lincoln was shot on April 14, 1865, and died of his wounds the next morning. News of his death spread widely and quickly, particularly because of the spread of the telegraph and the first transatlantic cable, laid in 1858. Here is a telegram I once found in the Dutch national archives.

King Netherlands Hague

Wednesday

President Lincoln has been assassinated and is very likely dead Mr. Seward and his son have also been mortally wounded by an assassin.

Baron Bentinck

London