noon
Upon the 21st both armies crossed the Tormes , the French at Alba and Huerta , the British at Aldea Lengua , and San Marta . Upon that day the news reached Wellington that General Chauvel , with 2000 cavalry , and 20 guns , would reach Marmont on the evening of the 22d , or the morning of the 23d , and the English general therefore resolved to retreat , unless Marmont should , by some mistake , give him a chance of fighting to advantage . Close to the British right , and the French left , were two steep and rugged hills , called the Hermanitos , or Brothers , and soon after daybreak on the 22d , the French seized upon the one nearest to them , while the British took possession of the other . Then , watching each other , the two armies remained until noon , for Wellington could not commence his retreat by daylight ; but a long cloud of dust along the road to Ciudad Rodrigo showed that the baggage of the army was already _ en route _ for Portugal . Marmont now determined to make a bold stroke to cut off Wellington 's retreat , and , although all his troops had not yet arrived , he ordered Maucune , with two divisions , to march round by the left and menace the Ciudad road . It was at three o'clock in the afternoon , and Wellington , who had been up all night , thinking that Marmont would make no move that day , had gone to lie down for an hour or two , when Tom Scudamore who , from an elevated point , was watching the movements of the enemy , hurried in with the news that the French were pushing their left round towards the Ciudad Road . Wellington leaped to his feet , and hurried to the high ground , where he beheld , with stern satisfaction , that Marmont , in his eagerness to prevent the British escape , had committed the flagrant error of detaching his wing from his main body .