It was not long before he was in the NHL. The Montreal Canadiens signed him in the summer of 1941. They brought the 5'9" and 165lb classic defender to the city for a couple of seasons of high level senior hockey. By 1942 he was a full time member of the Montreal Canadiens.
Sure, all NHL teams were missing players due to conscription and voluntary enrolment in the allied efforts in World War II. But make no mistake Glen Harmon was not just some fill-in. He would go on to an impressive nine year career in the NHL, winning Stanley Cups in 1944 and 1946. He followed that up with four more years of senior hockey, all in Montreal.
How good was he? These were the days before the NHL had a trophy for the top defenseman every year. The only true measure of blue line excellence is All Star status. In both 1945 and 1949 he was named to the NHL's Second Team All Stars. Hall of Famers like Butch Bouchard, Babe Pratt, Jack Stewart, Bill Quackenbush and Ken Reardon were also named to teams that year, along with high scoring dman Flash Hollett. That is some excellent company to keep.
Harmon was described as an excellent skater and a solid positional defender. He was a strong outlet passer and, despite his small size, a solid hitter.
But don't take my word for it. Let's here what his peers had to say:
Detroit coach Jack Adams: That boy Glen Harmon has put plenty of life into them....He's travelling all the time. He's got speed to burn. He clears pretty well, is shifty, and seems to give the team more pep than they ever had early on in the season.
And Montreal manager Tommy Gorman: "You know the most underrated player on the team? Glen Harmon! Boy, he's a dandy. He always gets a goal when it's badly needed, like the tying one in Toronto on Saturday. And he has been on the ice for only 16 goals scored against the club all season !"
It seems to me Glen Harmon was sort of a Brian Rafalski of his day. An excellent though undersized and underrated defenseman.