Short answers, pulled from the story.
The Battle of Laon took place on the 9th and the 10th of March 1814. The fighting began with a surprise counteroffensive by Blücher during the night of the 9th of March 1814 and concluded after Napoleon ordered his withdrawal on the evening of the 10th of March 1814.
Field Marshal Gebhard Leberecht von Blücher commanded the Allied Army of Silesia at the Battle of Laon. His forces included Prussian corps led by Friedrich Wilhelm Freiherr von Bülow, Generals Yorck and Kleist, as well as Russian units under Ferdinand von Wintzingerode, Langeron, and Osten-Sacken.
Blücher commanded approximately 90,000 troops and 176 guns during the engagement while Napoleon deployed only around 50,000 men total. French casualties reached at least 6,000 men including killed wounded and captured whereas Allied side casualties numbered at least 3,500.
Napoleon lost the Battle of Laon because his smaller force struggled with supply issues coordination problems and fatigue from previous engagements. The Allies utilized strong defensive positions on high ground to block French advances and inflicted significant casualties through devastating artillery fire.
The town of Laon rose over 100 meters above the surrounding countryside on a flat-topped hill that provided a commanding view for anyone holding its heights. This strategic location served as a key road junction dominating the terrain and allowed natural defensive advantages for the Allies to control movement across the region.