There seem to be a lot of World War I articles appearing recently, presumably as a lead-up to the centennial of the assassination of Archduke Franz Ferdinand of Austria on June 28, 1914, the proximate cause of the beginning of the war. If you're interested in further information on the subject there are hundreds of books and films - the best books I know of (and I'm no expert) are Barbara Tuchman's The Guns of August (this won a Pulitzer back when they meant something) and John Keegan's The First World War.
This animated map reflects the daily changes over the course of the war. I'd previously seen the WWII version (embedded below) but not this one.
Here's the The BBC’s Horrible Histories explanation of how the Brits got involved in WWI:
The Atlantic has a series of photoessays entitled World War I in Photos on various WWI topics - there will be ten of these, but they're not all available yet. Of those posted so far, I found technology and animals of particular interest.
Previous posts: Wilfred Owen, the best of the WWI "War Poets", was born 121 years ago today