qnli question: What was the shortest of the major battles fought during the stalemate? sentence: The principal battles of the stalemate include the Battle of Bloody Ridge (18 August–15 September 1951), the Battle of the Punchbowl (31 August-21 September 1951), the Battle of Heartbreak Ridge (13 September–15 October 1951), the Battle of Old Baldy (26 June–4 August 1952), the Battle of White Horse (6–15 October 1952), the Battle of Triangle Hill (14