While serving on the USS Monaghan, Dewey received new rates and awards for his service to his country. His first rating up was on November 16, 1942. The initial rate was an Apprentice Seaman (AS) to a Seaman 2nd class (Sea2c). From there, Dewey’s rate became a Seaman 1st class (S1c) on April 1, 1943. After being rated as a S1c, he received the new rate of Signalman 3rd class (SM3c) on April 1, 1944. He was only able to become a SM3c before his death. However, Dewey also received recognition through more than just higher ratings. On March 26, 1944 Dewey was initiated into Mysteries of the Deep for crossing the equator. After he died, he received the World War II Victory Metal.
Along with rating up, Dewey participated in many invasions, battles, and occupations. The first of these was on March 26, 1943 when Dewey engaged with Japanese troops off of the Komandorski Island. This is when he was awarded his Silver Star by his commanding officer. The next time Dewey was in action was on May 11, 1943. On this day, he was among the sailors that participated in the invasion of Attu Island. In the months of June–July of 1943, Dewey was apart of the blockade and patrol of Kiska Island, where they engaged and destroyed an enemy submarine. Finally in August, the crew was able to occupy Kiska Island. Then during November 20, 1943–December 5, 1943, the crew of the USS Monaghan were able to successfully invade and occupy the Gilbert Islands.
At the beginning of the following year, Dewey was also in the invasion and occupation of the Kwajalein Atoll Marshall Islands between January 29, 1944–February 8, 1944. Then on February 17,1944–March 2, 1944 he partook in the invasion and occupation of Eniwetok Atoll Marshall Islands. During this same time period, Dewey and the crew also bombarded Parry Island.
The summer of that year was also eventful for the USS Monaghan. Between June 11–19 of 1944, Dewey and the other sailors bombarded and occupied the Saipan Islands. This was done while being under enemy plane fire from the 17th to the 19th. Two days later on the 21 until the 27, they were bombarding and occupying another island, Guam Island. Once again, facing enemy plane fire. From June on all was quiet until December of 1944. At the time of the 14–16, the crew of the USS Monaghan were helping the Carrier Task Force by screening oilers. Two days later the ship was fatally hit.