Operation AXIOM: The World War
23-29 December 1916: The Christmas Battles—Imperial Russian infantry used surprise & the cover of a snowstorm to attack across the frozen Tīrelis swamp & breach the "German Wall" defensive line near Riga, seizing the Germans' strongest fortifications & taking over 1,000 prisoners; the offensive stalled when the 17th Siberian Regiment mutinied, presaging the coming February Revolution.
Commentary: Two years hence, In "The Explorers' Club" episode № CDXXIV, I described the "Christmas truce" of 1914 as "impromptu, unofficial, sporadic, & quite possibly the most fondly remembered episode of the whole awful war." It has been mythologized, possibly to an unhealthy degree. As a counterpoint, whenever you hear mention of the Christmas truce of 1914, remember the Christmas Battles of 1916: the Russians deliberately attacked at Christmas, when the Germans thought they'd be busy celebrating the holiday season.
The Latvian War Museum has preserved &/or restored much of the Tīrelis swamp & forest battlefield, available today for tours as the Museum of the Christmas Battles.
Lest we forget.