On 12 Jul 1861 Wilder, a farmer, mustered into service with the 15th Massachusetts Volunteer Infantry, being credited to the quota of Sutton, Worcester County, Massachusetts. He was 20 years, 10 months and 12 days old.
Wilder and David M. Daniels
, future brothers-in-law, served together in the 15th Massachusetts Volunteer Infantry in Co. G.
Wilder was wounded in the shoulder on 21 Oct 1861 at The Battle of Ball's Bluff, Leesburg, Virginia.
On 1 Apr 1862 Wilder was promoted to Corporal, and on 6 Jul 1862 Wilder mustered out of the 15th Massachusetts due to disability.
Wilder also served in the 36th Massachusetts Regiment starting 22 Aug 1862 as a 2nd Lieutenant and ended his service with the 36th by resignation on 31 Jul 1863.
On 30 Jun 1864 Wilder, 23, married Jane Melissa Paine, 23, daughter of Jonathan Wales and Lucena Paine, at Sutton, Massachusetts, in a first marriage for both. They had at least four children.
On 23 May 1865 Wilder's sister, Flora A. Holbrook, married David M. Daniels at Worcester, Massachusetts.
Wilder died on 27 Dec 1902 at Sutton, Worcester County, Massachusetts, of pneumonia. He was 62 years, 3 months and 27 days old.
An obituary for Wilder S. Holbrook was published on 28 Dec 1902 at the "Worcester Daily Spy
", as follows:
Mr. Wilder S. Holbrook died from pneumonia at his Sutton home Saturday morning.
Mr. Holbrook was a prominent and well-known resident of the town, being employed for years at the Cutsom House in Boston.
He was a former lieutenant of the Fifteenth Massachusetts Regiment.
His wife and three daughters, Mrs. Fred Smith of Smithville, Miss Alice Holbrook, a teacher in Morristown, N. J., and Miss Flora Holbrook, a student in Wellesley College, survive him....