Following his graduation, he spent a year at Carnegie Tech, before he received appointment to the United States Naval Academy at Annapolis, Maryland, in June 1926.

[3][2] Following his return from the exercise, Weller served for some time as Detachment Officer at Marine Barracks within Norfolk Navy Yard, before rejoined his 1st Battalion in January 1935.

During his service on Tuscaloosa, he simultaneously served as Control Officer of the 5"/25 caliber Anti-aircraft battery and used this opportunity to improve his knowledge of use of naval gun for support of the landing operations.

[1][2] After two years of sea duties aboard the Tuscaloosa, Weller returned to the 1st Battalion, 10th Marines at Quantico Base, Virginia, in June 1939 and was appointed commanding officer of "A" Battery.

Within this capacity, Weller took part in the extended Caribbean Maneuvers, in which 1st Brigade was transferred to Guantánamo Bay, Cuba to prevent expansion of Vichy French from Martinique.

In this capacity, Weller was tasked again with the reorganization of the Naval Gunfire Shore Fire-Control Party, the link between the supporting ship and the troop unit ashore.

[1][2] Lieutenant Colonel Weller received new orders in September 1942, when he was transferred to San Diego, California and appointed to the same capacity within Amphibious Corps, Pacific Fleet under Major General Clayton B. Vogel.

His battalion was assigned to the 3rd Marine Division under Major General Allen H. Turnage and Weller later received the Bronze Star Medal with Combat "V" and Navy Unit Commendation for his service on Bougainville.

Weller served simultaneously as naval gun officer for Task Force 51 under Vice Admiral Richmond K. Turner and had devised together with Lieutenant Colonel William W. Buchanan a modified form of the "rolling barrage" for use by the bombarding gunships against beachfront targets just before H-Hour.

[5] For his distinguished service with the Fleet Marine Force on Hawaii and during the Battle of Iwo Jima, Weller was decorated with the Legion of Merit with Combat "V" and received also the Navy Presidential Unit Citation.

[1][2] Weller left Quantico in July 1949 and entered Senior Course at the Naval War College in Newport, Rhode Island, one month later.

[1] Another interesting assignment came at the end of May 1956, when Weller was transferred to Paris, France and appointed Deputy Operations Officer to the Commander in Chief, European Forces under General Lauris Norstad.

Weller returned stateside during April 1958 and after a brief leave, he assumed duties as assistant chief of staff for personnel at Headquarters Marine Corps in Washington, D.C., under General Randolph M. Pate.

Because of the ongoing Laotian Civil War and worsening situation in Vietnam, he was tasked with the training and combat preparation of the division for Counter-guerrilla operations.