Austria-Hungary was the country which started the war by declaring war on Serbia in July 28, 1914. Earlier that year, Austria-Hungary had signed an alliance with Germany and Italy which was called the Triple Alliance (later called Central Powers when Italy left the alliance). Italy had joined the other alliance called the Triple Entente (Allies) which consisted of France, Great Britain, and Russia. The Allies were Austria-Hungary and Germany's enemies during the war. These alliances were the conflict that pulled in countries into the war which made Austria-Hungary one of the major sides involved in WWI. Some major battles were the battles of the Isonzo which were fought along the Isonzo River in Italy between June 1915 and November 1917. This was considered a big battle because throughout the big battle, there were 12 battles that made up the battle of Isonzo. The other major battle was the battle of the Piave River, fought between June 15-22, 1918 where Austro-Hungarian forces were weakened by this time. After the battle, Italy had suffered 150,000 casualties while Austria-Hungary had lost 40,000 in a week. Austria-Hungary suffered really bad, they lost about 1.5 million troops during WWI including around 500,000 that died as prisoners.