Marshal Belle-Isle remained with the sole charge of the defence of Prague; he was frequently harassed by the Austrians; his troops were exhausted with cold and privation.

During the night between the 16th and 17th of December, 1742, the marshal sallied from the town.

"I stole a march of twenty-four hours good on Prince Lobkowitz, who was only five leagues from me," wrote Belle-Isle, on accomplishing his retreat; "I pierced his quarters, and I traversed ten leagues of plain, having to plod along with eleven thousand foot and three thousand two hundred and fifty worn-out horses, M.de Lobkowitz having eight thousand good horses and twelve thousand infantry.

I made such despatch that I arrived at the defiles before he could come up with me.

I concealed from him the road I had resolved to take, for he had ordered the occupation of all the defiles and the destruction of all the bridges there are on the two main roads leading from Prague to Egra.