Historical clue formulations

• When both hands are up — 2023-01-12
• When the sun is highest in the sky — 2022-07-25
• When a nautical day begins — 2019-09-11
• When there's "darkness" in a classic Arthur Koestler novel — 2015-06-14
• Classic time to duel — 2014-12-17
• When some do lunch — 2012-12-19
• When shadows are shortest — 2012-07-20
• When duelists duel, sometimes — 2007-03-23
• When some hands join — 2006-12-22
• When two hands meet — 2005-10-21
• When some meet for lunch — 2004-10-01
• When there's darkness, in a Koestler title — 2000-11-06
• When there's darkness, in a Koestler title — 2000-04-05
• When shadows almost disappear — 1997-12-28