As the conflict entered its third winter, an Allied victory appeared remote and uncertain. The bloody four-month Battle of the Somme had sputtered out in the cold and rain of November with negligible gains. Despite strenuous efforts, the Italian offensives along the Isonzo River in 1916 had not succeeded in denting the Austrian line or pushing it back significantly. Hopes that Romania, which joined the Entente on August 17, 1916, would become a factor in the war had been quickly dashed when it was overrun by the Central Powers four months later. In June 1916 Russian armies under General Brusilov attacked the Austrians along a wide front, but their advance, which began with such promise, was thrown back when the Germans rushed troops to support their ally. When the fighting ended, the Russians had lost another million men and their army was practically finished. On the seas, German U-boats were taking an increasing toll on Allied and neutral shipping. Sir John Jellicoe, then C-in-C of the Grand Fleet, found it necessary to warn the cabinet that shipping losses on the present scale might drive the Allies out of the war by the early summer of 1917. Adding to this somber picture was the cost of the war, which had risen to about £5,000,000 a day. In the autumn of 1916 the Treasury revealed that Britain's reserves of gold and convertible securities were nearly exhausted and that soon it would have to finance the war with US loans.