The Lexington Minutemen will hold a dress rehearsal at 2 p.m. Sunday on the Battle Green to prepare for the annual Patriots Day reenactment. The historical reenactors will return to the town common for their showdown with the British at 5:30 a.m. April 15. The events marking the anniversary of the Battle of Lexington on April 19, 1775, which was the first of the Revolutionary War, typically draw thousands of spectators to the Battle Green and other area sites. The town will begin its weekend of Patriots Day observances on Saturday with a reenactment of “Parker’s Revenge,” in which Captain John Parker led the Lexington militia to ambush the retreating British soldiers near the Lincoln line hours after the first skirmish. Other events include tours of the Buckman and Munroe taverns, as well as the Hancock-Clarke House. Next Sunday, Lexington will hold a parade at 2 p.m. to celebrate the town’s 300th anniversary as well as Patriots Day, and at 11:30 p.m. there will be a reenactment of Paul Revere’s stop at the Hancock-Clarke House during his famous midnight ride to alert Colonial militia that the British were coming. An updated schedule of events is posted on the town’s website, www.lexingtonma.gov.