Birthplace:
- Edinburgh, Scotland

Birthdate:
- 10 June 1843

Nationality:
- Scottish

Height:
- 5 feet 11 1/2 inches

Family Background:
- Mackenzie's father was John Mackenzie, Treasurer of the Bank of Scotland

At Sandhurst:
- No

Career before Halifax:
- Ensign, 25 February 1862 (purchase)
- Lieutenant, 22 February 1864 (purchase)
- Captain, 8 July 1868 (purchase)

Postings while in NS Command:
- Halifax, June [?] 1869 to 9 July 1869
- Saint John, New Brunswick, 10 July 1869 to 3 August 1870
- Halifax, 4 August 1870 to November 1871

Married:
- Jeanette Sophie Falkenburg, Church of England, Quebec, 29 May 1869

Children:
- Christina Frederica Augusta (b. Edinburgh, 15 July 1870)
- Ian Duncan (b. Quebec, 27 June 1870)

Career after Halifax:
- retired by sale of commission, 17 July 1872

Died:
- March 1890

John Mackenzie, Treasurer of the Bank of Scotland, and Colin's father, was the son of Colin Mackenzie of Portmore House in Peebleshire, a Scottish county to the south of Edinburgh. The family was related to Charles Fraser of Castle Fraser, Aberdeenshire, and were thus descendants of Alexander Mackenzie-Fraser, one of the original founders of the 78th, and first commander of the second battalion which was raised in 1804. Colin Mackenzie III attended Harrow, and then studied mathematics, fortification, and modern languages under private tutors at home "with a view", wrote his father, "to his ultimately applying for admission into the army." Colin's first choice for a commission was in the 78th because it was "a Mackenzie regiment", and because of his ancestor's association with it.

While serving with the 78th in Quebec Mackenzie met and married Jeanette Sophie Falkenburg, the daughter of Count Gerhard Falkenburg, Norwegian Consul General in Canada. The ceremony took place on 29 May 1869. It, and then the pair's honeymoon to New York, delayed Mackenzie's joining his regiment in Halifax.

While in Halifax Mackenzie proved one of the regiment's most gregarious members. He joined the North British Society, the Masonic Order, and the Royal Halifax Yacht Club, and he took a leading part in organizing the Scott Centenary celebrations of 15 August 1871.

Mackenzie remained in the army for less than a year after leaving Halifax, retiring by sale of his commission on 17 July 1872. Thereafter, pursuing a more studious life, he became a member of the Royal Geographical Society, and of the Scottish Academy. He also aspired to write a history of the 78th, but died before this could be accomplished. The accounts of the regiment both in Keltie's History of the Scottish Highlands (1883) and in Davidson's History and Services of the 78th Highlanders (1901) are based upon materials collected, but not used, by him.