The men of the Middle Ages sometimes show the power of sizing up the strategic essentials of a large theatre of war which they had never seen, and had never even seen mapped. For instance, take the case of Philip Augustus’s advice to his son with regard to the campaign of 1216 in England, that is that the Prince should first of all seize the castle of Dover which commanded the English terminus to the shortest possible sea route between England and France.
In the present instance, the mobilization point and the line of march were intelligently chosen. It was clearly out of the question to cross the “Massif Central,” the mountains of Auvergne, since armies are compelled to seek the lines of geographical least resistance, and must avoid, whenever possible, thinly peopled districts which cannot keep them in food and shelter. The choice which faced the leaders of the Crusade was whether to outflank the mountainous country by the west or by the east.
It is only a guess, but I think that the decision to march by the easterly route was mainly for political reasons. To march by the west would have brought the crusading army close to territory still held by John of England. That monarch was still firmly planted on both sides of the lower Garonne, and had even held on to parts of Poitou well to the north of that river. The much widowed Raymond of Toulouse had married John’s sister Joan, who had since died. John had broken with the Pope over the candidacy of Stephen Langton, later of Magna Charta fame, for the archbishopric of Canterbury; and when Innocent had replied by interdicting all England, John had been able to compel most of the English clergy from enforcing the sentence. Since the Crusade was obviously directed against Raymond, John might move. It would be well, therefore, for the Crusaders not to give him an opportunity of falling upon their flanks or rear while marching south on the westward route.
Furthermore, there were geographical points to be considered. Crusaders from Germany and the Slavonic lands east of the Adriatic could more easily reach Lyons than, say, Limoges. Of course, most of the Crusaders would be “French,” that is North French, but German and Slavonic contingents were expected and did, in fact, turn up. East of the mountains, the expedition would be in closer touch with Rome, which might prove important in those days of slow couriers. Finally Lyons, being a large town, would be more suitable for a mobilization point than any smaller city further west, for cities draw armies like magnets since only in cities is there enough surplus food and shelter for large bodies of men. Lyons was, therefore, wisely chosen as the concentration point, and the Rhône Valley as the line of march.
The main force which assembled at Lyons was extremely large. The “Chanson de la Croisade” says twenty thousand knights and men-at-arms plus two hundred thousand “villeins” on foot. Until recently it has been fashionable for historians to disbelieve mediæval high numbers, but fashions change. At any rate, a huge army assembled.
The weakness of the great force was that only forty days’ service sufficed to fulfil the crusading vow. Hence the Crusade, if prolonged, was bound to suffer (like so many American armies from Washington’s to the Civil War) from the plague of short enlistments.
Besides the papal legates Arnaut Amalric and Milo, there were with the army the Archbishops of Reims, Sens, and Rouen, the Bishops of Autun, Clermont, Nevers, Bayeux, Lisieux, and Chartres, the Duke of Burgundy, and the Counts of Nevers and St. Pol.
Just how the higher command was organized we do not know. Arnaut Amalric seems to have been the strongest personality.
Inconspicuous, no doubt, among the lesser nobles was a Baron of the Isle of France, also Earl of Leicester in England, Simon de Montfort by name. Possibly people pointed him out as the only man in the Fourth Crusade five years before to refuse to march against Zara, so that when the Venetians persuaded the other Crusaders to pay for their passage to the East by taking this Christian city he had left the expedition and gone home. It seems quite clear, however, that at the beginning he was of little authority in the Crusade.
In the last week of June the Crusaders moved south from Lyons, keeping, apparently, to the east bank of the river where the main Roman road ran.