Heavy rainfall transformed the Waterloo battlefield into a treacherous swamp during the pivotal 1815 battle. A powerful storm began on the evening of June 17th and continued through the early morning, saturating the clay soil. This created extremely difficult conditions for soldiers, with reports of troops sleeping in water and artillery sinking into the mud. The adverse weather significantly impacted the battle’s progression, influencing Napoleon’s strategic decisions. The text indicates Napoleon reacted to the conditions, though the specific response isn’t detailed in this excerpt. The challenging terrain added another layer of complexity to the already fierce fighting at Waterloo.