Russia attacked on the Eastern Front on March 18th 1916, in a failed attempt to ease German pressure on France at Verdun.
A two-day artillery bombardment signalled the start of the Lake Naroch offensive, on the borders of present-day Lithuania and Belarus.
Despite outnumbering Germany’s Tenth Army, the Russians were heavily defeated in two weeks of fighting, suffering more than 100,000 casualties.
Attacking on a narrow front, they encountered problems familiar to their allies on the Western Front.
Often inaccurate shelling failed to destroy the German defences, leaving Russian troops exposed to gunfire as they attempted to advance in the mud of an early spring thaw.
The Lake Naroch offensive was launched in response to French calls for support at a critical moment in the First World War.
France, under intense pressure at Verdun since February 21st, appealed for action by its allies elsewhere to divert German attention.
Less than three months earlier, a conference of Allied commanders at Chantilly in December 1915 had agreed on the need for simultaneous attacks against the Central Powers in 1916.
Sources: Wikipedia/various