The host was organised in three separate camps, and Abu Sofian was placed at the head of the entire army. Each leader, however, was to have alternating command of the campaign; and this primitive arrangement--the only one, it seems, by which early nations, lacking an indisputable leader, can surmount the jealousy and self-will displayed by every petty chief--is responsible in great measure for their ultimate failure. In such fashion, still with the bravery and splendour of Eastern warfare wrapped about them, an army of 4000 men, with 300 horses, 1500 camels, countless stores, spears, arrows, armour and accoutrements, moved forward upon the small and factious city of the Prophet, whose fighting strength was hampered by the exhaustion of many campaigns and the disloyalty of those within his very walls. The Prophet was outwardly undismayed; whatever fears preyed upon his inner mind, they were dominated by his unshakable belief in the protection and favour of Allah. He did not allow the days of respite to pass him idly by. As soon as he received the news of this fateful expedition, he called together a meeting of his wisest and bravest, and explained to them the position. He told them of the hordes massed against them, and dwelt upon the impossibility of opposing them in the open field and the necessity of guarding their own city. This time there were no dissentient voices; both the Disaffected and the Muslim had had a lesson at Ohod that was not lightly forgotten. Then Salman, a Persian, and one skilled in war, suggested that their stronghold should be further defended by a trench dug at the most vulnerable parts of the city's outposts. Medina is built upon "an outcropping mass of rock" which renders attack impossible upon the north-west side. Detached from it, and leaving a considerable vacant space between, a row of compactly built houses stood, making a very passable stone wall defence for that portion of the city. The trench was dug in that level ground between the rocks and the houses, and continued also upon the unsheltered south and east sides. There are many legends of the digging of the trench and the desperate haste with which it was accomplished. Mahomet himself is said to have helped in the work, and it is almost certain that here tradition has not erred. The deed coincides so well with his eager and resolute nature, that never neglected any means, however humble, that would achieve his purpose. The Faithful worked determinedly, devoting their whole days to the task, and never resting from their labours until the whole trench was dug. The hard ground was softened by water, and legendary accounts of Mahomet's powers in pulverising the rocks are numerous.