CHAP. HI.] ROMAN CAVALRY. 63 



up a position with his army about five miles south-east 

 of Placentia, cutting off the communication of the 

 Roman Consuls with Rome and Ariminum. The Romans 

 then marched out of Placentia to the west, and crossed 

 the Trebbia and camped on its left bank, probably to be 

 near the towns in which their magazines and supplies 

 were stored. 



Hannibal again used his Numidians to bring on an 

 action on ground of his own choosing, where he had 

 facilities for preparing an ambush, from which a detach- 

 ment could fall upon the flank and rear of his opponents 

 at the crisis of the action. The Numidians were sent to 

 lay waste the country in the neighbourhood of the 

 Roman camp. Sempronius (who commanded the 

 Romans) led out his cavalry and a large body of archers 

 and drove them back to their lines, and after a heavy 

 skirmish Hannibal drew off his troops and left Sempro- 

 nius elated with an apparent success. 



In the night he placed his brother Mago with 2,000 

 picked soldiers, half infantry and half cavalry, in the 

 bed of a watercourse, in front of his right flank, where 

 they were perfectly concealed. At the break of day, 

 before the Romans had been tible to eat their morning 

 meal, he sent his Numidians across the river to threaten 

 their camp, and to endeavour to entice them into a 

 general action. Sempronius fell blindly into the trap. 

 He sent his cavalrv to attack the Numidians, ordered 

 out 6,000 archers on foot to follow his horsemen, and at 

 length in person led the remainder of his army out of 

 their entrenchments. The success of the previous day 

 had rendered him vainly confident. It was mid-winter, 

 very cold, the Trebbia was swollen breast-high, the 

 Romans were fasting. Hannibal awaited them on his 

 own ground, his men warm and fresh and vigorous, well 

 fed and in high spirits. In face of all this Sempronius 

 led his men through the swollen stream, and with an 

 army enfeebled with the cold, fought a general action 

 with a river in his rear. 



This battle of the Trebbia is a convincing proof of 

 the fact that Hannibal owed nearlv all his successes to 



