Nor must the Greeks be forgotten. With all the defects of their Army, many detachments fought valiantly, especially the Serres Division, which, fighting under the British, distinguished itself at the battle of Doiran and suffered severe losses. The French and Serbian cavalry, once the breach had been made, were in the vanguard of the pursuit, and pushed forward by forced marches which have few equals in the annals of the war. 3. The perfect co-operation between armies of different nationalities, a co-operation which Sarrail had never been able to achieve. This was one of General Franchet d’Espérey’s main successes. There were, in fact, the Central Franco-Serbian Group, composed of 6 Serbian Divisions and 2 French; the I Group of Divisions, with 1 French, 2 Greek, and for a short time 1 British Division; the A.F.O., comprising 5 French, 1 Italian, and 1 Greek Division; the British Army with 3, and afterwards 4 British, 5 Greek Divisions, and one French Regiment. Nevertheless everything functioned regularly as if it had been a perfectly homogeneous force. 4. The faulty dispositions of the enemy. Although, as we have seen, the latter were stronger in effectives than the Allied forces, they had failed to create reserves. In Bulgaria there were only three regiments available, and the Germans had withdrawn all their battalions from the Balkan front, except three, to which a few others were added during the offensive. In Serbia and Roumania, the German and Austrian garrisons were numerous, but they were composed of units whence nearly all the younger soldiers had been withdrawn. The enemy thus had only small area reserves, and no army reserves. When the central sector was broken through the enemy Command tried to stem the advancing tide by concentrating regiments withdrawn from distant sectors, such, for instance, as the 14th, which was notorious for its mutinies; but it was then too late. Only in the Doiran sector, where some of the best regiments were collected, was it possible to hold up the British and Greeks for a few days, and also in the Cerna loop, where the German Command made its influence more directly felt, and there the resistance was more vigorous.