the California Column invaded Arizona from the west. The Californians under Colonel James H. Carleton captured the Confederate Fort Yuma on traditional Arizona's side of the Colorado River. No fight occurred as the rebels' cavalry garrison retreated into Mexico before Colonel Carleton's arrival. The Californians then moved on, using the old Butterfield Mail route as their path. Tucson's garrison was then tasked with delaying the Union invasion from the west. The garrison burnt several hay stations, which were actually former mail stations, abandoned before the war. Californians and Confederates under Second Lieutenant John W. Swilling fought the small Battle of Stanwix Station. Gradually, Union pickets made their way to the Pima Villages. A force of eight Federal troops were captured there by the Confederates without conflict. Before the Californian invasion, the Union had sent spies into the region, with the mission of procuring supplies of food and hay for the California Column. The supplies were stored in the abandoned Butterfield Mail stations, with one cache in the Pima Villages. Once Carleton's main body reached the Pima Villages, they discovered that their much needed food had been taken by Confederate forces and resold to the Pimas. Having gone too far to turn back, the Californians advanced on Tucson. Confederate pickets were waiting for the Union advance at Picacho Peak. Their mission was to wait for the California Column, and upon sighting it, return to Tucson to alert Captain Sherod Hunter and his men. An advance Union cavalry patrol discovered the rebel camp at Picacho Peak and attacked. The Battle of Picacho Peak was fought, and the Union cavalry retreated back to their main body. At this time, Tucson was at the verge of falling, with no Confederate reinforcements having arrived in Tucson. Sherod Hunter, with only a company and some Tucson militia, was facing a Union army of over 2,000. As victory was impossible, most of the garrison withdrew just before the Capture of Tucson. A squad of Confederate troops were ordered to remain behind, under command of a Lieutenant. These men narrowly escaped the Union advance on the city. The lieutenant later reported that the Californians surrounded Tucson and then launched a full attack with infantry and cavalry, fully expecting to fight a battle. The Union troops entered the town as the column's band played Yankee Doodle. The rebels almost put up a fight but were dissuaded by an unknown