Trigg helped raise a new militia company in Bedford County in 1775[3] and became one of its offices, with the rank of lieutenant.
He was promoted to lieutenant colonel in 1791, and in 1793 served as a major in the Second Battalion of the Tenth Regiment of the Virginia militia.
Bedford voters elected him as one of their representatives in the Virginia House of Delegates, and re-elected him several times so he served (part-time) from 1784 until 1792.
At this time, Trigg, a Democratic-Republican/Anti-Federalist was in the minority party, as the House was majority Federalist, as was John Adams, the President of the United States.
After the President's speech, which caused an uproar among Anti-Federalists as not being sympathetic enough to France and too hawkish,[7] the House debated until May 31 on their response to his address.
In the 1787 Virginia tax census, he owned nine enslaved teenagers, eight enslaved adults, six horses, a two wheeled carriage and 40 cattle in Bedford county, where William Trigg (possibly his father or brother) owned eight teenage slaves, eight adult slaves, ten horses and 33 cattle.
[13] This John Trigg may not be the nonresident of Berkeley County on Virginia's northern border who paid taxes on two horses and two other livestock but no slaves.