He was captured during Battle of Lundy's Lane in July 1814 and held prisoner of war in Massachusetts until March 1815.

[1] After the war, Merritt purchased 25 acres (10 ha) at Shipman's Corners, where he built a house and a store.

In 1816, he bought a rundown sawmill on the Twelve Mile Creek, and added a grist mill and a store.

In 1818, when the flow was especially low, Merritt pursued the idea of bringing water to his mills from the Chippawa Creek.

[2] Although he first conceived the canal in 1818, his own personal business troubles in a general depression delayed his ability to work on the proposal.

He organised public meetings to garner support, issued a circular outlining the proposal, and lobbied the provincial government.

Merritt was a passenger on the first ship that made the entire transit, departing from Lake Ontario on November 30, 1829, and arriving at Buffalo, New York on December 2, 1829.

[5] In 1832, Merritt was elected to the Legislative Assembly of Upper Canada in a by-election, representing Haldimand County.

He also favoured developing the new transportation system, railways, and proposed a rail link between Montreal and the Maritimes.

Merritt was elected to the new Legislative Assembly of the Province of Canada for Lincoln North as a Reformer.

[8] In 1843, there was a political crisis between the Governor-General, Sir Charles Metcalfe, and the Lafontaine-Baldwin ministry, which resulted in Baldwin and Lafontaine resigning.

The Governor-General tried to pull together a new ministry which would attract moderates from all political views, provided they did not push for responsible government.

Metcalfe and the leader of the moderate Tories, Henry Draper, both considered that Merritt's participation would be essential, given his broad political support in the Niagara region and his breadth of knowledge about transportation issues.

In the early 1840s, he financed the establishment of both a Methodist (the second version still stands) and a Baptist church for Black refugees, and sold lots to the refugees themselves at below market prices, according to [10] Merritt's son, a city councilor, successfully pushed the city to compensate the so-called " Negro Village" that flourished around the churches, after many buildings were burned during an anti-Black riot in 1853.