The Second Battle of Fort Defiance was a military engagement fought during the United States period of the Navajo Wars.

On April 29, 1860,[3] about 1,000 Navajo warriors assaulted the United States Army garrison of Fort Defiance in New Mexico Territory,[1][4] now within present day Arizona.

The Navajo achieved a surprise attack but was ultimately repulsed by 150 American defenders of the 3rd Infantry under Captain Oliver L. Shepherd.

The Americans formed in the center of the buildings and withstood the Navajo attack.

[citation needed] It was also one of the reasons why the militia commander Lieutenant Colonel Manuel Antonio Chaves ordered an unauthorized campaign into Navajo territory in 1860 and 1861.