When the Great War began in 1914, the U.S.—much to the relief of many citizens—was insulated from the complicated morass of alliances that brought Europe to the trenches. Americans could watch from afar, safe in their neutrality, while benefiting from providing supplies for the Allies.
But, even though President Woodrow Wilson had been reelected in 1916 on the strength of his having maintained that peace, there came a point at which he could no longer support the isolation of the United States from the conflict of World War I. After the sinking of the Lusitania, the interception of the Zimmermann Telegram and the return of unrestricted submarine warfare, the time had come.
On April 2, 1917, Wilson went before Congress to request a declaration of war. By April 6, exactly a century ago Thursday, both houses had approved the resolution and war on Germany was officially declared. (War on Austria-Hungary was declared later.) The world would never be the same.
Here’s how Wilson made the case for war: