The acquisition of Jardine Lloyd Thompson Group PLC will strengthen Marsh LLC in several key areas in North America, according to executives at the newly combined brokerage.

JLT was strong in Western Canada, particularly municipal and government business, said Martin South, president of the United States and Canada division at Marsh in New York. And the brokerage had deep expertise in energy and power, construction, aerospace and financial lines insurance, added Patrick Donnelly, a former senior JLT executive who was named head of unified brokerages North American specialty operations in December.

JLT “has excellent depth in some areas” and brings “extra depth and breadth into the organization,” Mr. South said.

The executives were speaking at a press conference during the Risk & Insurance Management Society Inc.’s annual conference in Boston on Tuesday. The acquisition of JLT by Marsh was finalized earlier this month.

The two brokerages had relatively little overlap in clients, with Marsh providing services to about 200 of JLT’s 3,000 clients, Mr. South said.

And while several senior former JLT executives have left the combined firm in recent weeks, “we will fight for our clients,” he said.

One of the most high profile departures was Mike Rice, executive chairman of JLT Specialty USA, and formerly a longtime Aon PLC executive, who left the brokerage last week, sources say. Marsh declined to comment on his departure.