At Colombey the battle resolved itself into a desperate struggle along the front of the French position, where the Prussians made little impression, while their losses considerably exceeded those inflicted on the French" (Clery). It is thus seen that the commander of the Advanced Guard must limit his aggressive action in accordance with his instructions and with the tactical and strategical requirements of the force he is covering. But his action in _protecting_ the Main Body is unfettered by any considerations of prudence, and must ever be vigorous and resolute, any risks being taken that ensure the safety of the Main Body. On the morning of the _Battle of Nachod_ (June 27, 1866) the Advanced Guard of General Steinmetz's V. Corps (of the Army of the Crown Prince of Prussia) was in bivouacs on a plateau, after emerging from a long and narrow defile through which the Main Body must march to the open country beyond. About 8 a.m. the cavalry of the Vanguard was checked by the advanced troops of the VI. Austrian Corps. It was imperative that the Prussian Advanced Guard should hold the plateau until the Main Body had extricated itself from the defile. By the rapid and accurate fire of the infantry and horse artillery, and the co-operation of the cavalry against the Austrian squadrons, the thin line was maintained for more than three hours. Less than 7 battalions of infantry, with 13 squadrons of cavalry and 3 batteries of light artillery, kept in check 21 battalions, 11 squadrons, and 4 batteries. Had the Advanced Guard suffered itself to be driven back on the Main Body in the defile a disaster could scarcely have been avoided, and owing to the steadfast endurance of the Advanced Guard the Main Body was able to drive the Austrian Corps from the field. ADVANCED GUARD PROBLEMS.--The Advanced Guard commander must be able to appreciate without delay {111} the situation which confronts his force, and to solve the problem before him with regard solely to the interests of the force he is covering. (a) If the Vanguard is held up by the enemy who is ascertained to be inferior in strength to the Advanced Guard, the commander will transmit information to the Main Body and will attack vigorously to disperse the enemy, in order that the movements of the Main Body may not be delayed. A fire attack would be organised on the front of the enemy, supported by close-range artillery fire, and a turning movement with Lewis guns and rifles on one or both flanks. If the enemy held to a covered position they could be ejected by rifle bombers or light mortars from a flank, while artillery and machine guns prevented aimed fire at the attacking force.