His method of catching wolves was simple and unique. He would build an oblong, pyramidal log pen about eight by sixteen feet at the base, and eight feet in height, the last layer of logs being placed about eighteen inches apart. Easily climbing the slope of this, the wolves would jump down through the narrow aperture at the top to feed upon the quantities of meat that had been placed inside to decoy them, but they could not jump out. Often, of a morning, the trapper and his sons would find ten or more big wolves imprisoned in the trap, and, powder and ball being very costly, they would kill them with bow and arrows, skin them, and drag the carcasses to the river and cast them into it, then take the hides home and peg them on the ground to dry. In this manner they would often, in the spring, have several hundred wolf pelts to pack in to Fort Benton for sale, and prime pelts sold at five dollars each, in trade. Their catch of beaver, otter, mink, martin, and fisher was also large.
Monroe always camped at the foot of the lower lake, near the outlet, and was there more than once attacked by roving war parties of Assiniboines, Crows, and even the Yanktonais. The horses were kept at night in a strong corral just back of the lodge, and in the daytime were watched by some member of the family while they grazed on the rich prairie grasses. All the family--John and François, the sons, Millie and Lizzie, the daughters--and even the mother had guns, flintlocks, and a good supply of powder and ball. Early one morning a large war party was discovered approaching the camp, sneaking from bush to bush, some crawling on all fours through the high grass. Lizzie opened fire upon them and killed her man, and then the fire became general on both sides. But the Monroes, in their trenches surrounding the lodge, had the best of it from the start, and eventually made the enemy retreat with a loss of five of their number. Late the following night the Assiniboines crept in to make another attack, but the Monroes were expecting them, waiting for them, and in the bright moonlight could take fairly accurate aim. They again drove them off, with a loss of two more of their number, and that time they kept going. Nothing more was seen of them. But for some days the Monroes did not venture far from their camp.