[4] In September 1911, Munroe was transferred to the Charleston Navy Yard, South Carolina, where he served on the staff of Reserve Torpedo Division and completed submarine training.

He was promoted to Lieutenant (junior grade) on June 6, 1913, and ordered to the Puget Sound Navy Yard for duty in connection with fitting out of submarine USS H-3 three months later.

He then led her during the patrols along the West Coast of the United States with the Pacific Fleet until November 1914, when he was transferred to the Bureau of Steam Engineering in Washington, D.C., where served as an Inspector.

Munroe was promoted to Lieutenant on August 29, 1916, and was ordered back to the Puget Sound Navy Yard, where he had duty in connection with fitting out of coastal submarine USS N-3.

Munroe then assumed command of the submarine and patrolled off the Panama Canal Zone against possible U-boat attack and returned to San Francisco, California, in February 1919.

[4] Munroe served with Paul Hamilton within Pacific Fleet until June 1927, when he was ordered to the Naval War College at Newport, Rhode Island, for senior course.

His command took part in the patrols in the Pacific ocean and along the West Coast of the United States and Munroe was ordered for instruction to the Army War College at Fort Humphreys in Washington, D.C., in July 1937.

He led his division, consisting of battleships Mississippi, New Mexico and Idaho within the Neutrality Patrols in the Atlantic Ocean during the ongoing War in Europe.

[9][10] Following the Japanese attack on Pearl Harbor and United States entry into World War II, Munroe was promoted to Rear Admiral on December 8, 1941, and his command continued in the operations in the Atlantic and returned to Pacific in mid-1942.

He then conducted patrols between Hawaii and the West Coast of the United States and was transferred to Miami, Florida, in March 1942 for duty as Commander, Gulf Sea Frontier and Seventh Naval District.

[11][12] While in this capacity, Munroe was responsible for the protection of both coasts of Florida, the Gulf of Mexico, the Yucatan Channel, and most of Cuba and directed antisubmarine campaign against German U-boats penetrating to the Caribbean.