President Abraham Lincoln had supported the Republicans when Juárez was in power, but was unable to help them due to the Civil War that was raging in the United States at that time. As soon as that conflict ended, U.S. Army General Philip Sheridan, under the supervision of President Andrew Johnson and General Ulysses S. Grant, gathered 50,000 soldiers and deployed them on the Mexican border. In that area, they carried out dramatic patrols, threatening intervention against the French (but at the same time also supplying arms to the Republican guerrillas). The United States Congress unanimously approved a resolution condemning the restoration of the monarchy in Mexico (April 4, 1864). On February 12, 1866, the United States formally asked France to withdraw its troops; the Americans moved units to positions on the Rio Grande and implemented a naval blockade to prevent the French from landing any reinforcements. They also protested to Austria over the presence of its volunteers (May 6).
