Gilbert Blanchard was mustered into the 7th New Jersey Volunteers, Company K on October 2, 1861 on a three year term. He was transferred to Company C at some point during his term, though there is no evidence to corroborate when.

He was captured by Confederate troops and sent to the Andersonville POW camp in Georgia, where he died of dropsy (endema), most likely caused by extensive malnutrition. His death date is documented as August 13, 1864.

He is buried in Andersonville National Cemetery in Andersonville, Georgia.