First. The generalissimo renewed the order for strengthening the fortifications of Warsaw and Praga, as well as those on the whole plain of Grochow. From the first day of April, as many as 5000 Russian prisoners were continually employed upon those fortifications. Warsaw, which was already, as the reader is informed, defended by a girdle of lunettes and redoubts, communicating with each other, received the additional defence in some places of block-houses. To strengthen the fortifications of Praga, besides the bridge-head, there were constructed, within the distance of an English mile, a line of circumvallation, which could hold more than twelve thousand men. Still farther, at a distance of two miles beyond, or nearly upon the field of Grochow, was constructed a third line of lunettes and redoubts, which occupied the whole distance from Kawenczyn to the marshes of Goclaw, or the entire field of battle of Grochow, as seen in the plan of that battle. In fine, the approach to Praga was so defended, that the enemy, before reaching it, would have to pass three different lines of fortification. The general in chief gave instructions to the governor of Warsaw in regard to the defence of the city, in which he placed his chief trust upon the national guard. The guard counted it an honor to be entrusted with this duty, and were unwilling that a single soldier of the regular army should be detailed for the service. How admirably they executed their noble resolutions, when the occasion came, is probably well known to every reader.