In the winter of 1807, the French Army of the Republic found itself quartered in the freezing, desolate woodlands near Cottbus, Polabia. The conditions were brutally punishing for the French soldiers, who suffered from severe malnutrition, hypothermia, and a lack of adequate shelter in the abandoned town of Heinrichsfeld. Despite the dire state of his men and the warnings of his generals, Davout and Morel, Gaspard Lefebvre remained unbothered by the cold and dangerously dismissive of the Polabian threat. Believing the enemy was too battered from their previous defeat at Woikowitz to mount an offensive, Gaspard ignored reports that the Polabians held the high ground and were hidden within the dense forests. He confidently arrayed his forces around the town, placing the II and III Corps on a forested hill to the left, the IV and V Corps to the center and right, and holding General Dubois’ elite Cavalry Guard in reserve.

This complacency was shattered at 5:00 AM on December 7th when the Polabian army launched a massive, unexpected artillery bombardment. The French, who had falsely assumed the Polabians abandoned their cannons during their previous retreat, were pinned down and massacred by relentless canister shot. Awakened by the carnage, Gaspard ordered General Lefrancois to haul French artillery pieces into the upper floors of Heinrichsfeld’s buildings to return fire against the elevated, obscured enemy. Frustrated by the invisible Polabian positions and acting on Gaspard's broad operational discretion, Generals Aubert and Morel ordered the 24,000 men of the II and III Corps to march up the hill at 9:30 AM to seize the initiative.

This uphill advance played perfectly into the hands of the Polabian commander, General von Steinwehr, who had deliberately waited for the French to settle before springing his trap. As the French trudged through the thick snow, 33,000 Polabian infantrymen emerged from the treeline, unleashing a devastating and disciplined rate of volley fire that cut the French ranks to pieces. By noon, the II and III Corps were fundamentally broken, routing back down the hill toward the town in total disarray. To prevent the collapse of his left flank, Gaspard ordered Lefrancois’ IV Corps to abandon the center and reinforce the routing divisions. Though Lefrancois vehemently protested leaving the right flank exposed, he obeyed, and his fresh troops successfully halted the Polabian advance, capitalizing on the Wendics' exhaustion and frozen hands.

However, disaster simultaneously struck the French right flank. General Breard, commanding the V Corps, sought personal glory by attempting an unauthorized flanking maneuver up a snowy path he believed would lead to the Polabian rear. Instead, his marching columns were ambushed by Polabian Cuirassiers. The heavy cavalry tore through the exposed French lines, cutting the V Corps in half and forcing a chaotic, bloody retreat back to the town. By 4:00 PM, the French army was on the verge of total annihilation; three of its corps were shattered, and Gaspard was beginning to feel hopeless. Realizing that the Polabian lines had to be broken immediately, General Dubois volunteered to lead the 7,500-strong Cavalry Guard in a desperate frontal assault.

Advancing blindly through a sudden blizzard, the French heavy cavalry smashed into the surprised Polabian infantry, inflicting massive casualties and capturing standards. But as the blizzard abruptly cleared, the cavalry was exposed to point-blank Polabian artillery fire, which decimated the horsemen and wounded Dubois. Seeing the gap created by the cavalry’s sacrifice, Lefrancois immediately ordered the IV Corps into a bayonet charge, plunging the center of the battlefield into a horrific, disorganized melee of hand-to-hand combat. By 6:20 PM, both armies were entirely exhausted. Witnessing the carnage and knowing that his Austrian allies would not come to his aid, King Joachim Harrach II ordered a reluctant General von Steinwehr to withdraw. The Polabians retreated overnight, leaving the French with a pyrrhic victory that cost them 18,000 casualties compared to Polabia’s 7,500. Shaken by the slaughter but holding the field, Gaspard marched on Berlin a week later, prompting the Polabian King to sue for peace. The War of the Third Coalition officially ended in early 1808, with Polabia aligning with France and Bavaria signing a separate treaty, leaving Britain completely isolated once again.