On the south of Paris, between the Seine and Meudon, are first a line of forts, then a line of redoubts, except where Chatillon cuts in close by the Fort of Vanves.

Beyond this line of redoubts is a plain, that slopes down towards the villages of L'Hay, Chevilly, Thiais, and Choisy-le-Roi, which is situated on the Seine about five miles from Paris.

By Monday evening about 100,000 men and 400 cannon were massed under General Ducrot in the Bois de Vincennes and in the adjacent villages.

About 15,000 men, under General Vinoy, were behind the southern line of redoubts close by the village of Villejuif.

Troops were also placed near St.Denis and in the peninsula of Genevilliers to distract the attention of the enemy.