by Edmond Thomas Quinn in 1915, is in the park, along with French's Minute Man statue. The American Battlefield Trust and its partners have saved one acre of the battlefield at the site of Parker's Revenge. Four current units of the Massachusetts National Guard units (181st Infantry, 182nd Infantry, 101st Engineer Battalion, and 125th Quartermaster Company) are derived from American units that participated in the Battles of Lexington and Concord. There are only thirty current units of the U.S. Army with colonial roots. Several ships of the United States Navy, including two World War II aircraft carriers, were named in honor of the Battle of Lexington. Commemorations Patriots' Day, an observed legal holiday is celebrated annually in honor of the battle in Massachusetts. It is recognized by that state, as well as by Connecticut, Maine, and by the Wisconsin public schools, on the third Monday in April. Re-enactments of Paul Revere's ride are staged, as are the battle on the Lexington Green, and ceremonies and firings are held at the North Bridge. Centennial commemoration On April 19, 1875, President Ulysses S. Grant and members of his cabinet joined 50,000 people to mark the 100th anniversary of the battles. The sculpture by Daniel Chester French, The Minute Man, located at the North Bridge, was unveiled on that day. A formal ball took place in the evening at the Agricultural Hall in Concord. Sesquicentennial commemoration In April 1925, the United States Post Office issued three stamps commemorating the 150th anniversary of the Battles at Lexington and Concord. The Lexington—Concord commemorative stamps were the first of many commemoratives issued to honor the 150th anniversaries of events that surrounded America's War of Independence. The three stamps were first placed on sale in Washington, D.C. and in five Massachusetts cities and towns that played major roles in the Lexington and Concord story: Lexington, Concord, Boston, Cambridge, and Concord Junction (as West Concord was then known). This is not to say that other locations were not involved in the battles. The events were also commemorated on the 1925 Lexington-Concord Sesquicentennial half dollar. Bicentennial commemoration The Town of Concord invited 700 prominent U.S. citizens and leaders from the worlds of government, the military, the diplomatic corps, the arts, sciences, and humanities to commemorate the 200th anniversary of the battles. On April 19, 1975, as a crowd estimated at 110,000 gathered to view a parade and celebrate the