Thus in five weeks one of the French field armies was imprisoned in Metz, the other destroyed, and the Germans were free to march upon Paris. This seemed easy. There could be no organized opposition to their progress,[4] and Paris, if not so defenceless as in 1814, was more populous. Starvation was the best method of attacking an overcrowded fortress, and the Parisians were not thought to be proof against the deprivation of their accustomed luxuries. Even Moltke hoped that by the end of October he would be "shooting hares at Creisau," and with this confidence the German III. and IV. armies left the vicinity of Sedan on the 4th of September. The march called for no more than good staff arrangements, and the two armies arrived before Paris a fortnight later and gradually encircled the place--the III. army on the south, the IV. on the north side--in the last days of September. Headquarters were established at Versailles. Meanwhile the Third Empire had fallen, giving place on the 4th of September to a republican Government of National Defence, which made its appeal to, and evoked, the spirit of 1792. Henceforward the French nation, which had left the conduct of the war to the regular army and had been little more than an excited spectator, took the burden upon itself. The regular army, indeed, still contained more than 500,000 men (chiefly recruits and reservists), and 50,000 sailors, marines, douaniers, &c., were also available. But the Garde Mobile, framed by Marshal Niel in 1868, doubled this figure, and the addition of the Garde Nationale, called into existence on the 15th of September, and including all able-bodied men of from 31 to 60 years of age, more than trebled it. The German staff had of course to reckon on the Garde Mobile, and did so beforehand, but they wholly underestimated both its effective members and its willingness, while, possessing themselves a system in which all the military elements of the German nation stood close behind the troops of the active army, they ignored the potentialities of the Garde Nationale.