Historical clue formulations

• W.W. I helmet — 2026-03-29
• Soldier's helmet, in old slang — 2024-02-11
• W.W. I helmet, informally — 2022-08-07
• W.W. I headgear — 2021-05-01
• Stereotypical wear for the paranoid — 2014-09-06
• Doughboy's headgear — 2012-07-18
• Helmet from W.W. I or W.W. II — 2009-04-27
• Doughboy's topper — 2007-11-04
• G.I.'s helmet, slangily — 2007-10-23
• W.W. I helmet, informally — 2007-05-27
• Soldier's helmet, slangily — 2006-03-05
• Soldier's helmet — 2005-05-01
• Soldier's helmet, slangily — 2004-05-17
• G.I.'s headgear, slangily — 2001-10-30
• Soldier's helmet — 1998-03-14