Consequently, this short timeline gives a page to each year of the war, with bookends from the years before and after. The closing dates of battles are given alongside starting dates for faster access and, because some people use timelines to quickly and easily grasp the range and spacing of events, I've added more explanatory detail than is usual for the war years.
Where the reference books disagree over a particular date, I have cited Colin Nicholson's excellent Longman Companion to the First World War, Europe 1914 - 1918; I also favour the dates people/plans started moving, rather than when they were first signed off by commanders. For example, the British government decided to withdraw from the Gallipoli Landings on December 7th, but I have noted December 10th as the start, because this was when troops first began to leave.
The following are used when the region is not immediately obvious: WF: Western Front
EF: Eastern Front
IF: Italian Front
SF: Southern Front
BEF: British Expeditionary Force
CEF: Canadian Expeditionary Force
USW: Unrestricted Submarine Warfare