TOM HORTON traces the key moments in the First World War

Austria-Hungary sends troops to the Serbian border. Austria-Hungary declares war on Serbia. A Royal Navy cruiser is sunk by German mines in the North Sea, killing 150 men and inflicting the first casualties on Britain. Defence of the Realm Act (DORA) gives the UK government sweeping powers to suppress public criticism and imprison people without trial in order to aid the war effort. Japan declares war on Germany and British Army troops see their first land action in the Battle of Mons. Britain and the Ottoman Empire declare war on each other. The first Zeppelin raid on London kills seven people. Battle of Loos begins and the British forces use gas for the first time, however wind blows it back onto their own troops, killing seven and injuring 2,625.