In one small tent, in the camp of the Seventh Infantry, the first boom stirred up a young man who had been sleeping, and he may have been dreaming of home. He was in the uniform of a second lieutenant, and in one respect he was exactly like all the other younger officers and most of the men of that army, for never before had they heard the sound of a hostile cannon. War was new to them, and they were not aware how many of them were now entering a preparatory school in which they were to be trained for service in a war of vastly greater proportions and for the command of its contending armies, on either side. Up sprang the young lieutenant and stepped to the door of his tent. He was short, strongly built, and his alert, vigorous movements indicated unusual nerve, vitality, and muscular strength. "Grant, my boy," he muttered to himself, "that comes from the fort! The Mexicans are attacking! It's more than twenty miles away. I didn't know you could hear guns as far as that, but the wind's in the right direction. Hurrah! The war has begun!" He was only half right. The war had been begun long years before by aggressive American settlers in the Spanish-Mexican State of Texas. Now, at last, the United States had taken up the same old conflict, and only about half of the American people at all approved of it. Grant did not linger in front of his tent. He walked rapidly away to where stood a group of officers, hardly any of them older than himself. "Meade," he demanded of one of them, "what do you think of that?" "I think I don't know how long that half-finished fort can hold out," responded Lieutenant Meade, and half a dozen other voices instantly agreed with him as to the perils surrounding the small besieged garrison. It was hardly possible, they said, that it could hold out until the arrival of the main army. This, too, would have to fight all the way against superior numbers, but that was a thing which it could do, and they were all wild with eagerness to be on the march, in answer to the summons of those far-away guns.