While researching the records of Dalhousie, I found that Archibald's older brother, William, was enrolled in the local militia.
"Under the Militia Act of 1793 . . . each male inhabitant aged 16 to 50 was required to enroll his name as a militiaman and attend annual muster on the King's birthday, 4 June. Each captain was required to present his colonel with a written roll for transmission to the Lieutenant Governor within 14 days of 4 June . . ."(1)
"On 7 November 1828 the Adjutant General's Department of Upper Canada ordered the officers commanding each regiment of the province's sedentary militia to submit a nominal roll of the men in their units from 19 to 39 years of age."(2)
At the time of the 1828 nominal roll, William was 25 years old, and his father, Robert, was 47 years old. According to the Militia Act, both were required to attend the annual militia muster. However, the nominal roll that year only required the listing of men from 19 to 39, so Robert was not listed. William was numbered in the 1st Regiment Lanark Militia in Captain Cumming's Company. This company was from Dalhousie.
1. Bruce S. Elliott, et al., Men of Upper Canada Militia Nominal Rolls, 1828-29 (Toronto, Ontario: Ontario Genealogical Society, 1995), iii-iv.
2. Elliott, Men of Upper Canada, iii.