The battalion, which was composed mainly of African-American troops, served in the Pacific Theater of Operations during World War II, when it was known as the 91st Engineer General Service Regiment.

On 16 October 2013, it was assigned to the 1st Brigade Combat Team, 1st Cavalry Division, and activated at Fort Hood, Texas.

[3] The 91st Engineer Battalion (Separate) departed the New York Port of Embarkation on 4 March 1942 and arrived in Brisbane on 9 April.

[5] By December 1943, it was the only major US engineer unit in the Port Moresby area, and was charged with a full range of base maintenance functions.

[3] The 91st Engineer Battalion was reactivated at Fort Hood, Texas, on 16 October 1992, this time as part of the 1st Cavalry Division.

[8] The 91st Engineer Battalion was deactivated at Fort Hood on 8 July 2005 as a result of the transformation of the United States Army.

[1] A silver color metal and enamel device 1 1/8 inches (2.86 cm) in height overall consisting of a shield blazoned: Gules, a plate charged throughout with a masoned stone arched bridge Proper.

From a wreath Argent and Gules a demi-sunburst Or charged with a fountain fimbriated Tenné, overall an Indonesian kris hilt to base Proper.

The kris, a typical weapon of Indonesia and Papua, symbolizes that region of the Pacific and its significance during World War II.