The document summarizes key events leading to the U.S. entry into World War I. Germany began sinking neutral ships in 1915, violating international agreements and killing over 100 Americans on the Lusitania. Further attacks on ships with American passengers in 1916 and an intercepted message proposing a German alliance with Mexico in 1917 outraged the American public. On April 2, 1917, the U.S. declared war on Germany to help ensure freedom of the seas and "make the world safe for democracy."