The first world war, except on land, was led on the seas. The countries that participated in the battles were divided into two groups - the forces of Antante and the Central Power forces. Antant was made up of Great Britain, France, Russia, USA and from 1915 Italy. On the opposite side were Germany, Austria-Hungaryan empire, Turkey and Bulgaria. The main locations in which the battles took place were on the Atlantic Ocean, the Mediterranean Sea, the Black Sea and the Baltic Sea. The balance of power between the forces before the beginning of the war was on the side of the allies. Of all the battles that took place in the war, only the submarine war brought some benefits to the Central Forces. The submarines on the Atlantic managed to submerge a large number of military or civilian vessels that were sailing to Britain. Those on the Adriatic Sea managed to maintain a war balance, and only in the Baltic and the Black Sea did not yield almost any results. In the end, the war on the seas was determined by German outstretchness on all seas and the economic and military power of the countries of the Antante force. The moment when the end of the war became just a matter of time was the entry of the United States into war in late 1917. The rest of the war was spent in a constant defensivness of the Central Forces and their final defeat at the end of 1918.