[1] The original dish was named to celebrate the Battle of Marengo,[2] a Napoleonic victory of June 1800.
According to a popular myth, the dish was first made after Napoleon defeated the Austrian army at the Battle of Marengo at Marengo south of Alessandria, Italy, when his chef Dunand foraged in the town for ingredients (because the supply wagons were too distant) and created the dish from what he could gather.
[1] This colorful story, however, is probably myth; Alan Davidson writes that there would have been no access to tomatoes at that time, and the first published recipe for the dish omits them.
[3] The more plausible explanation for the origin of the dish is that it was created by a restaurant chef in Paris[4] to honor Napoleon's victory.
[3] Pellegrino Artusi's recipe in his Science of Cooking and the Art of Eating Well is as follows (it lacks tomatoes, crayfish and eggs):