In less than an hour, sufficient forces had crossed the bridges to justify the officers in ordering an advance against the first line of the enemy trenches that had been established just within the edge of the forest. The trenches were heavily manned and bristled with field and machine guns, while back of them in the grim and forbidding forest stretched other lines of defense that the boys knew would cost thousands of American lives to take. But the job was there and had to be done. And they vowed in their hearts that it should be done. The huge tanks lined up for the attack and got once more in action. Into the woods they went, crushing down trees as though they were pipe stems, lurching into and out of shell craters, tearing into the barbed wire entanglements, plucking up the posts to which they were fastened and opening huge gaps into which came pouring the long lines of shouting, cheering men. Like an avalanche they struck the trenches, and the Germans poured out to meet them. The opposing lines swayed back and forth like gladiators in a death grip. Then they broke up into hundreds of battling groups, a dozen men here, twenty there, struggling with bayonets and rifle butts, hacking, stabbing and at times throwing their empty guns aside and fighting with knives and even with fists. It was the kind of close-in fighting in which the Americans excelled and which they always sought when the plan of battle made it possible. Frank, Tom and Billy fought as closely in company as they could, and many a blow had been warded off by one of the three from the others that would otherwise have found its mark. For a long time the battle seemed to be fairly even, for the Germans fought with the fury of desperation and were constantly reinforced from heavy divisions kept in reserve. Each side attached especial importance to this first stage of the fight, because of the influence it might have on the morale of their men. The side that lost in the first phase of the battle would be depressed, while the side that won would be correspondingly elated and strengthened in spirit for the struggles that were yet to come. But American blood and American fighting qualities were not to be denied. Gradually the Germans were pressed back, but as they retreated they kept up a stubborn resistance by means of machine gun nests posted in every conceivable place, at every turn in the forest paths, in clumps of bushes, in forks of trees. They made the Americans pay dearly for every foot of ground that they gained. But the Americans had learned by long experience not to advance in mass formation against these messengers of death. They spread out in units and in groups, worming their way through the bushes, seeking the shelter of every rock and tree and shell hole.