On a field near the Belgian village of Waterloo, a Napoleon re-enactor, riding a white horse, gave orders to hundreds of people in military uniform. “Vive l’Empereur!” they shouted back.

The stand-in Napoleon, wearing a black bicorne hat, looked just like the real Napoleon, sharing his 5-foot-6 height, angular nose and light gray-blue eyes.

There was one big difference: He was not French, but American — an American with a French accent that is “quite horrific,” said Arnaud Springuel, an organizer of the annual battle re-enactment.

“For me, it’s not a problem,” Mr. Springuel said. “But the public doesn’t expect that from Napoleon,” he said.

For the 210th anniversary of the Battle of Waterloo, the organizers held their biggest re-enactment in a decade, with 2,200 actors restaging the battle last weekend before 17,000 spectators.

Mark Schneider, born on Long Island, secured the job over other would-be Napoleons, including from Belgium and Italy, in part because of his unrivaled ability to command respect on the battlefield, several organizers said.