The Germans now became a menace on the borders of the wood, where they impinged on a number of awkward pockets or little salients. The Americans in the wood enjoyed no sinecure, but were engaged in continuous skirmishes against groups of the enemy. One small pocket the Germans found too untenable under American fire on the northern side of the wood and hastily vacated it on June 19, 1918, enabling the Americans to advance five-eighths of a mile without resistance. A short and sharp artillery fire on the position presaged an infantry attack, which the Germans elected not to face. They carried their material with them in their retreat, and the Americans, therefore, did not take any machine guns nor prisoners. On the morning of June 21, 1918, the Americans straightened their line further on the northern and eastern side by a series of small but effective attacks. They rushed the positions held by the enemy without the customary artillery opening. The Germans for the most part fired a few shots and retired. Members of one post alone held their ground, only to be annihilated. To the east a thin line of American skirmishers obtained the objective in view there by merely firing as they advanced. Still the borders of the wood were not clear of the Germans. On June 23, 1918, the Americans directed their attention to the northwestern corner, where the Germans held positions that appeared impregnable. The Americans, in a night attack, started a heavy barrage, after which they went forward and drove out the Germans. The operation lasted only half an hour. Another engagement that took place in the same quarter on the same day was more extensive in scope though local in object. It resulted in the Americans advancing their lines a distance of 200 to 400 yards on a front of one kilometer, routing the Germans out of several hidden gun nests, and the capture of five machine guns. The fighting was marked by certain features, described by Edwin L. James: "This fight, which lasted four hours, was not accompanied by artillery or gas fire, and was mostly close hand fighting, the kind which Americans most prefer. It was a fight such as seldom occurs in this war, where usually trench positions are so well defined that barrages can be laid safely by both sides down to a matter of inches. "Germans and Americans got so mixed up in the north end of the Bois de Belleau that neither side risked using artillery for fear of killing its own men. "The Americans began to advance at 6 o'clock in broad daylight. In the extreme north wood the Germans had been able to establish some machine guns, which were firing against us. Our men advanced against these positions and discovered that to the north of the wood the Germans had established a strong line position." As to the ubiquitous machine guns, the Americans found that the Germans had organized such posts with great ingenuity: