After landing, he marched with rapidity toward Three Rivers, but was led by treacherous guides into a morass, and obliged to return back nearly two miles. Day broke, and he was discovered from the ships. A cannonade was opened upon his men as they made their way slowly for an hour and a half through a swamp. At length they arrived in sight of Three Rivers, but it was to find a large force drawn up in battle array, under General Frazer, by whom they were warmly attacked, and after a brief stand thrown in confusion. Thompson attempted to rally his troops, and partly succeeded, until a fire was opened upon them in rear by Nesbit, who had landed from his ships. Their rout now was complete. General Thompson, Colonel Irvine, and about two hundred men were captured, twenty-five were slain, and the rest pursued for several miles through a deep swamp. After great fatigues and sufferings, they were able to get on board of their boats, which had been kept from falling into the hands of the enemy. In these they made their way back to the Sorel, bringing General Sullivan a sad explanation of all the firing he had heard, and the alarming intelligence of the overpowering force that was coming up the river. “This, my dear general,” writes Sullivan, in the conclusion of his letter, “is the state of this unfortunate enterprise. What you will next hear I cannot say. I am every moment informed of the vast number of the enemy which have arrived. I have only two thousand five hundred and thirty-three rank and file. Most of the officers seem discouraged, and, of course, their men. I am employed day and night in fortifying and securing my camp, and am determined to hold it as long as a person will stick by me.” He had, indeed, made the desperate resolve to defend the mouth of the Sorel, but was induced to abandon it by the unanimous opinion of his officers, and the evident unwillingness of his troops. Dismantling his batteries, therefore, he retreated with his artillery and stores, just before the arrival of the enemy, and was followed, step by step along the Sorel, by a strong column under General Burgoyne.