“Bayonet! One! Two! Three! Four!” The commands ring out in a quiet Medford neighborhood near the Tufts University campus. Four men stand in formation on the worn lawn of a house at Capen Street and Hillsdale Road. They lunge with bayonets. They swing sabers with gloved hands. They spar with wooden “single sticks.” They aim their replica rifle-muskets. With every move, leader Paul Kenworthy’s orders break the tranquillity: “Shoulder, arms!”; “Rally by fours!”; “Thrust! Develop! Guard!” On Tuesday nights, this is the practice ground for the Salem Zouaves, a group of militia reenactors together since 2000. The Zouaves, who will be at the Salem Maritime Festival August 4, honor the Salem Light Infantry, one of many such companies that protected Massachusetts towns in the old days. When the Zouaves are practicing, they can sometimes be heard marching through the streets. Neighbors are well familiar with their drills, but that wasn’t always the case. The cops, acting on a report about men with guns, once swarmed the house. Two hundred years ago, the Zouaves might have fought back. This standoff dissolved into laughter.