The U-boat Campaign from 1914 to 1918 is the World War I naval campaign fought by German U-boats against the trade routes of the Allies. It takes place largely in the seas around the British Isles and in the Mediterranean.
Great Britain declares war on Germany, claiming that they invaded Belgium, a neutral country, on their way to invading France.
The Battle of Stallupönen is fought between Russian and German armies. This is the opening battle of World War I on the Eastern Front.
The Battle of Verdun, held between the German and French armies, becomes the largest and longest battle of the First World War on the Western Front.
The initial day of this battle, 1 July 1916, remains the most costly day in the history of the British army. It suffered almost 60,000 casualties, over a third of whom were killed. The name "Somme" has since become synonymous with slaughter.
The American entry into World War I comes in April 1917, after more than two and a half years of efforts by President Woodrow Wilson to keep the United States out of the war.