It was late in the day before battle was joined. Napoleon had reached Fleurus at about ten o'clock in the morning, but it was four hours more before he had brought all his troops across the river, and by the time he had done so two things had happened. First, the Duke of Wellington (who, as we shall see later, had come to Quatre Bras that morning, and had written to Blucher telling him of his arrival) rode off in person to the Prussian positions and discussed affairs near the windmill of Bussy with the Prussian Commander-in-chief. In this conversation, Wellington undoubtedly promised to effect, if he could, a junction with the Prussians in the course of the afternoon. Even without that aid Blucher felt fairly sure of victory; with it, he could be perfectly confident. [Illustration: The Prussian concentration before Ligny, showing the junction of the First, Second, and Third Corps on the morning of June 16th, and the inability of the Fourth Corps to come up in time.] As matters turned out, Wellington found himself unable to effect his junction with Blucher. Ney, as we shall see later, found in front of him on the Brussels road much heavier opposition than he had imagined, but Wellington was also surprised to find to what strength the French force under Ney was at Quatre Bras. Wellington, as we shall see, held his own on that 16th of June, but was quite unable to come up in succour of Blucher when the expected victory of that general turned to a defeat. The second thing that happened in those hours was Napoleon's discovery that the Prussian troops massing to oppose him before Ligny were going to be much more than a single corps. It looked to him more like the whole Prussian army. It was, indeed, three-quarters of that army, for it consisted of the First, the Second, and the Third Corps. Only the Fourth, with its headquarters at distant Liège, had not been able to arrive in time. This Fourth Corps would also have been present, and would probably have turned the scale in favour of the Prussians, had the staff orders been sent out promptly and conveyed with sufficient rapidity. As it was, its most advanced units got no further west, during the course of the action, than about halfway between Liège and the battlefield.