Howe's Mortars, 3d Marines ????
Marine regiments are designated - and referred to as - "Marines" in the same manner that army regiments are designated - and referred to as - "Artillery", "Infantry" "Cavalry", etc. This was common practice long before it became official policy in 1933. The 3d Marines is - and has been since 1942 - an element of the 3d (not the 1st) Marine Division. During operations at and around the Chosin Reservoir in Korea in 1950 the 11th Marines - the division's artillery regiment - was forced to spike its guns and its personnel were reorganized into provisional rifle companies and distibuted among the division's three rifle regiments. Each of the regiment's four battalions was alloted a battery of 4.2" mortars (commonly called "four-deuces"). Likewise, each of the division's three rifle regiments were alloted a company of "four-deuces". In addition, each rifle battalion had a platoon of 60-millimeter mortars, sections of which were parceled out among the rifle companies. I have a history of operations in Korea that goes into a good deal of detail and there's no reference to "Howe's Mortars".
There was an action at Hill 891 near Chinhumg-ni, later renamed How Hill, 5-6 November 1950 (this was during the withdrawal from the Chosin). The 1st Platoon, 1st Reconnaissance Company and elements of 3d Battaion, 7th Marines were engaged (Battery L, 11th Marines was attached to the 3d Battalion as a provisional rifle company). That may be the basis of your information.