When Napoleon III arrived to take command of the French field army, he followed the urging of his generals and ordered General Lebœuf to besiege Saarbrücken. Following a vigorous defense the outnumbered Germans evacuated the city, which the French occupied without crossing the river Saar. Lebœuf had been warned by his chief Intendant, Charles Joseph Francois Wolff, not to cross the Saar because they would be unable to supply men on the further bank. Therefore, the armies of France, led by Field Marshal Bazaine. took up defensive positions that would protect against every possible attack, but which also left their armies unable to support one another.