There was one possibility to be considered. Though Wellington was convinced that the French would concentrate north of the Douro, in the direction of Valladolid and Medina de Rio Seco, it was just conceivable that they might take the other course of concentrating south of the river, round Medina del Campo, and marching straight on Salamanca with all the troops that could be hastily drawn together. It was impossible for them to gather their whole force in the few days that would be at their disposition; but conceivably they might think it worth while to make a counter-stroke with such divisions as could be got together in haste. It is interesting to know that such an idea did flash through Jourdan’s mind for a moment, only to be rejected by King Joseph on the advice of the other generals[471]. Should the French march on the Tormes, a grave responsibility would be placed on Hill’s head. He was told to give them battle ‘if he was strong enough’--i. e. to judge their force according to the best information to be had, not an easy thing, but Hill was pre-eminently clear-headed and averse to unnecessary risks. Should they be too numerous, he was not to retire on Rodrigo by the route by which Wellington had come, but to throw up his communication with that fortress, and move off in the direction of Zamora, carrying out at all costs the plan for the junction of the two wings of the army[472]. Nothing was to remain behind to cover the Ciudad Rodrigo road and the Portuguese frontier but the single Spanish division of Carlos de España: all convoys on the march from Salamanca were to be turned off towards Ledesma and Zamora. It might look perilous to leave Central Portugal unprotected, but Wellington was sure that the enemy would be so distracted by his great movement north of the Douro, that they would not dare to advance on Ciudad Rodrigo and Almeida, to strike at his old line of communications. Moreover, it would not matter if they did, for his new line of communication was now entirely north of the Douro, and Oporto, not Lisbon, would be his base. On the 29th at dawn Wellington rode off to the north-west, almost unattended, and Hill’s responsibility began. It was not to turn out a heavy one, since (as his chief had foreseen) the enemy was not in the least thinking of taking up the offensive, but was rather expecting a continuation of the British advance from Salamanca. It did not come, and before the French had made up their minds as to what the halt of the southern column might mean, they were attacked on the 30th by the northern column, whose existence had hitherto been hidden from them. Hill therefore had only to wait for Wellington’s directions to march northward, when the date and route should be given. These orders did not come till the 2nd of June, so that the southern corps had to remain for a week in its own cantonments round Salamanca, doing nothing more than watch the French, north and east, by means of cavalry reconnaissances.