Sgt. MacIsaac's final taste of combat was in the little-remembered combat fought in Operation Commando. Operation Commando was an American-planned limited offensive to try and alleviate some of the combat being fought at Bloody Ridge and The Punch Bowl further east. This offensive also came with the acute need to prevent a huge Communist supply buildup, which could have resulted in another large-scale offensive against the UN forces. Line Jamestown, the UN designation for the Chinese front line, was the designated target, running from the Imjin River to a bit west of Chorwon. 

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The Chinese were well dug in, with huge amounts of supply and men available to hold out with. The attack began at 6 AM, October 3rd with the 8th Cavalry in reserve along Line Wyoming. The 5th Cavalry Regiment took the left flank and the 7th Cavalry Regiment the right flank as they advanced. The Chinese had erected huge, sprawling bunkers covered in as much as 15 feet of logs and earthworks with trench networks stringing them together on each of the mountainsides. On October 5th, the 8th Cavalry Regiment moved up to the right flank, securing Hill 418. 

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Four days later, with the Chinese beginning to crack, Sgt. MacIsaac was killed in action. While moving up a slope in the vicinity of Hill 346, MacIsaac's squad was pinned down by intense weapon fire. In the true spirit of heroism, he stood up and exposed himself to the Chinese bullets multiple times, encouraging his men to move forward and take the hill. He spotted targets for them and called on each one to continue the assault. It was while he stood tall in the face of the enemy that a bullet found its mark and mortally wounded the young man from Woburn. For his actions on October 9th, he earned the Silver Star Medal.