The document summarizes the start of World War 1 in Europe, beginning with Austria-Hungary declaring war on Serbia and setting off a chain reaction of countries honoring their alliance treaties. By mid-August 1914, the two sides were the Allied powers of Britain, France and Russia against the Central Powers of Germany and Austria-Hungary. The war quickly resulted in trench warfare along the Western Front in northern France, with new weapons like tanks, planes and chemical weapons leading to massive casualties but little movement in the battle lines.