With America thrust into the war, the President became interested in creating an American counterpart to the British Commandos in the Marine Corps. (Indeed, some reports tell that the Raiders were initally going to be called the 'Marine Commandos'.) The Commandant of the Marine Corps, Major General Thomas Holcomb, killed two birds with one stone and combined Carlson's guerrilla proposal with the President's Commando idea. (Carlson had the President's ear as well, having befriended FDR's son, Captain James Roosevelt.) By the end of February 1942, two Raider Battalions had been established. Carlson was given a promotion to Lieutenant Colonel and placed in command of the 2nd Raider Battalion. The commander of the 1st Raider Battalion, Lt. Col. (later, Major General) Merritt A. "Red Mike" Edson, had previously been in charge of a unit used to practice landing techniques and various new ideas.
The Raiders were given the best of the Marines' equipment, and were handpicked from available volunteers. Carlson's unit took a different direction than Edson's; Carlson borrowed some of the principles learned from his years with the 8th in China. Lt. Col. Carlson infused his men with elements of the Communist philosophy, treating officers and enlisted men equally, even to the point of using the phrase 'Gung-ho!' as a rallying cry.. However, the 1st had a unique structure as well, set up by Edson in his pre-Raider days. Edson still held true to traditional Marine Corps doctrine in most ways, and the two Battalions were quite dissimilar. It seemed the only thing they had in common were their names and status as elite units.
Both battalions were put into action at roughly the same time. Carlson's 2nd boarded the USS Nautilus and the USS Argonaut and performed a raid on Makin Island, a small Japanese base in the Pacific. The success of the raid was debatable; though the Japanese force was almost entirely wiped out, the intention was to divert Japanese men and materiel to smaller bases like Makin instead of larger targets (i.e. Guadalcanal), and the overall effect of the raid in that respect was questionable. The operation (being a raid rather than a full invasion) was quick, and casualties were relatively light, including nine men unintentionally left on the island when the Raiders returned to the submarines.
Meanwhile (several days earlier), Edson's 1st (along with the 1st Marine Division and others) hit the beach on the Solomon Islands. Operation Watchtower, in sharp contrast to Makin, would last several months and prove to be some of the toughest fighting of the Pacific Campaign. After their initial capture of Tulagi, the Raiders were moved to Guadalcanal. One of their most notable battles was on "Edson's Bloody Ridge", where the 1st Raiders, remnants of the 1st Parachute Battalion, and the 2nd of the 5th Marines scored a major tactical victory over Imperial Japanese Army forces.