There was serious danger that the government of Greece would follow the lead of Bulgaria and also enter the war on the side of the Central Powers. This was prevented by two things. In the first place, a majority of the Greek people favored the cause of the Allies and were opposed to Bulgaria. In the second place, the Allies promptly landed an army at Salonica. Later on, they removed Constantine, the pro-German king of Greece, and placed his son Alexander upon the throne. THE EAST AT THE CLOSE OF 1915.--On the eastern front 1915 had been a year of failure. The Gallipoli campaign had been a humiliation for the Allies. The Russians had been driven from Russian Poland and from the Austrian province of Galicia. Bulgaria had joined the Central Powers, linking Austria-Hungary with Turkey. Serbia, the country whose quarrel had been the occasion of the whole world struggle, had been conquered by the enemies of the Allies. ITALY ENTERS THE WAR.--In May, 1915, Italy declared war upon Austria, and more than a year later upon Germany. Her reasons for this action were: (1) her old enmity toward Austria; (2) her desire to annex the neighboring territory inhabited by Italians, but ruled by Austria; and (3) her feeling that Austria was opposed to Italian interests in the Balkans. Italy entered the war with vigor although at a great disadvantage. When the northern Italian lands were freed from Austrian rule in 1866, Austria kept the highlands and mountain passes, from which she could easily descend upon the Italian lowlands. Now that war was begun, the Italians were compelled to force their way up the heights and against the fire from well-protected Austrian forts. Here upon the dizzy peaks of the Alps, or the icy surfaces of glaciers, or the rocky mountain sides, warfare has been more spectacular and has called for more daring and recklessness than anywhere else. Slides of rock and avalanches of ice sometimes have been the ammunition of armies. During the year the Italians made some progress and by December occupied positions well within the Austrian frontier; but no decisive battle had been fought or important city or fortress occupied. ALLIED CONTROL OF THE SEA.--Throughout 1915--as in the preceding and the following years--the Allies maintained their control of the ocean. As a result of a proclamation declaring the North Sea a military area, and the more strict enforcement of the proclamation against sending contraband articles to Germany, the blockade against the Central Powers was more tightly drawn.