Historical clue formulations

• Cry "Uncle!" — 2020-01-15
• Call it quits ... with a hint to 17-, 23-, 48- and 56-Across — 2013-10-16
• Give up — 2005-04-18
• Cry uncle — 2001-12-21
• What boxer #2 then had to do — 1999-03-10
• Buckle — 1998-05-05
• Quit — 1996-12-26