The canon de 75 modele 1897 was a 75-millimeter piece of artillery invented by the French and employed by France and its allies in World War I and II. The cannon was quick firing, mobile and carried a punch, capable of launching a 12-pound shell at targets more than five miles away. Its use at the First Battle of the Marne in September 1914 cemented its reputation, where it earned the grim nickname "Black Butcher" from soldiers of the Kaiser.
About 12 years after its murderous performance at the Marne, legendary publican Harry MacElhone, owner of Lost Generation haunt Harry's American Bar in Paris, is said to have bestowed the honorific "French 75" on a mixture of gin, simple syrup and lemon juice, shaken and poured into a chilled flute, then topped with champagne. As the writers at http://ginfoundry.com put it, "The gun was known for its accuracy and speed, and the French 75 is said to have such a kick that it felt like being hit by just such a weapon."
Ginfoundry.com goes further, tracing its origins as far back as Dickens' England, when gin was king and the author himself was known to serve it mixed with bubbly to his guests.
Charles Dickens, the French Army and Harry are enough recommendation for us. We mixed our French 75's with the reasonably priced $19.95 Boodles London Dry Gin (first distilled in 1845, when Dickens was 33) and Schloss Biebrich sekt sparkling wine ($5.99 at Trader Joe's and a nod to the Jerries who fell to the Black Butcher at the Marne).
There's a lot of hype around the French 75—the cocktail even makes an appearance in Casablanca—all of it well earned. Objectively, though, it violates all the rules of responsible drinking: mixing wine with liquor, the inclusion of sugar syrup and carbonation, and the only mixer is lemon juice. In a case of "you have to know the rules to properly break them," the resulting combination is light, lively and only semi-sweet. Plus, it has an added bonus of icy citrus-tinged bubbles, which refresh as the gin warms and relaxes. However—and this is a big one—it's important to remember the French 75 is named for a weapon capable of hurling 15 rounds per minute, so consider no more than two rounds an hour with its liquid counterpart.