The importance of the operations of the Americans on the Marne sector was evident from the fact that the day before they arrived on the front and began fighting, the Germans advanced about six miles. While the Americans advanced their line, the French completed the capture of Vilny, Veuilly-la-Poterie, and the heights southeast of Hautevesnes. BELLEAU WOOD ENGAGEMENT Following the capture of Bouresches came the fierce fighting for the possession of Belleau Wood to the north. This wooded hill was a stronghold of German infantry and machine gunners, and the only way to attack it was by advancing to the other side. The American infantry had the assistance of the artillery in clearing the wooded heights, and in the biggest artillery engagement in which the Americans had yet been engaged more than 5,000 high explosive and gas shells were thrown into the German machine gun nests in the woods. Meanwhile German attacks against Hill 204, west of Château-Thierry and commanding the town, were repulsed. The United States marines attacked again on the morning of June 10 and penetrated the German lines for about two-thirds of a mile on a 600-yard front in Belleau Wood, with the result that the Germans were driven from all but the northern fringe of the wood. On June 11 the wood was captured and 300 prisoners were taken. FIRST FIELD ARMY The War Department received reports on May 21 which showed that the first of the field armies had been organized and was in service in France. The army, composed of two army corps, each made up of one regular army, one National Guard, and one National Army division, was placed under the temporary command of Major Gen. Hunter Liggett, the senior Major General then in foreign service. General Liggett was selected to command the first army corps organized in France, and this corps, with that temporarily commanded by Major Gen. Charles T. Menoher, made up the first field army, the total strength of which was almost 200,000 men. By June 14 the American forces in France had become so numerous that General Foch had informed General Pershing that it was desirable to maintain them as purely American units. This fact was communicated to the House Military Affairs Committee by the War Council at Washington. In accordance with this policy two full American divisions were engaged in the fighting in the Château-Thierry sector. The Secretary of War told the committee that General Foch was gradually decreasing the number of Americans brigaded with the French and British, and thereby increasing the American unit.