Comments by "Evan" (@MrEvanfriend) on "USMC: Structure United States Marine Corps Division in 1944 (F-100 Series)" video.
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As a former 03, you ought to know most of the differences. First, we now have LAR, AMTRAC, and Recon battalions per division. Also, the "three regiments per division" thing is purely theoretical - 3rd MarDiv has one actual regiment, 3rd Marines at K-Bay, and one regiment (4th Marines) on Okinawa that doesn't actually have any battalions (1/4 and 2/4 are at Pendleton, 3/4 is at Twentynine Palms). 3rd MarDiv also lacks a tank battalion. Pioneers don't seem to exist any more, or if they do I sure never heard of them. And obviously, weapons companies are organic to infantry battalions instead of just having one company at the regimental level.
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