The carelessness of the Christino picket, and the practice which the Carlists had already had in a warfare of stratagem and surprise, enabled the company of light infantry to execute, with great facility, the instructions they had received. The young ensign who commanded the outpost was walking listlessly along the edge of the wood, cursing the wearisome duty entrusted to him, and referring to his watch to see how far still the hour of relief was off, when he was suddenly struck to the ground by a blow from a musket-butt, and before he could attempt to rise, the point of a bayonet was at his throat. At the same instant three score long-legged Navarrese dashed from under cover of the wood, bayoneted the sentinels, surrounded the picket-house, and made prisoners of the picket. The surprise was complete; not a shot had been fired, and all had passed with so little noise that it appeared probable the _coup-de-main_ would only become known to the Christinos when the time arrived for relieving the outposts. A trifling oversight, however, on the part of the Carlists, caused things to pass differently. A soldier belonging to the picket, and who was sleeping amongst the long grass, just within the wood, had escaped all notice. The noise of the scuffle awoke him; but on perceiving how matters stood, he prudently remained in his hiding-place till the Carlists, having collected the arms and ammunition of their prisoners, began to reascend the mountain. At a distance of three hundred yards he fired at them, and then scampered off in the contrary direction. His bullet took no effect, and the retreating guerillas, seeing how great a start he had, allowed him to escape unpursued. But the report of his musket spread the alarm. The pickets right and left of the one that had been surprised, saw the Carlists winding their way up the mountain; the vedettes fired, and the drums beat to arms. The alarm spread rapidly from one end of the valley to the other, and every part of it was in an instant swarming with men. Dragoons saddled and artillery harnessed; infantry formed up by battalions and brigades; generals and aides-de-camp dashed about hurrying the movements of the troops, and asking the whereabouts of the enemy. This information they soon obtained. No sooner was the alarm given, than Zumalacarregui, relying upon the tried courage of his soldiers, and on the advantage of his position, which must render the enemy's cavalry useless, and greatly diminish the effect of the artillery, put himself at the head of his two battalions, and rapidly descended the mountain, dispatching an officer after Gomez with orders for a similar movement on his part. Before the Carlists reached the plain, the Christinos quartered in the nearest village advanced to meet them, and a smart skirmish began.