Germany's resumption of submarine attacks on passenger and merchant ships in 1917 was the primary motivation behind Wilson's decision to lead the United States into World War I. Following the sinking of an unarmed French boat, the Sussex, in the English Channel in March 1916, Wilson had threatened to sever diplomatic relations with Germany, unless the German Government refrained from attacking all passenger ships, and allowed the crews of enemy merchant vessels to escape from their ships prior to any attack. On May 4, 1916, the German Government had accepted these terms and conditions in what came to be known as the “Sussex pledge.”
Stunned by the news, President Wilson went before Congress on February 3 to announce that he had severed diplomatic relations with Germany. However, he refrained from asking for a declaration of war because he doubted that the American public would support him unless there was ample proof that Germany intended to attack U.S. ships with no warning. Wilson left open the possibility of negotiating with Germany if its submarines refrained from attacking American shipping. Nevertheless, throughout February and March 1917, German submarines targeted and sunk several American ships, and many American passengers and seamen died.
On February 26, Wilson asked Congress for authority to arm American merchant ships with U.S. naval personnel and equipment. While the measure would probably have passed in a vote, several anti-war Senators led a successful filibuster that consumed the remainder of the Congressional session. Despite the rebuff from Congress, Wilson decided to arm American merchant ships by executive order, claiming that an old anti-piracy law gave him the authority to do so.
While Wilson weighed his options regarding the submarine issue, he also had to address the question of Germany's attempts to cement a secret alliance with Mexico. On January 19, ...