Key to victory in the Pacific Theater during World War 2 was control of the vital waterways between the various islands making up the burgeoning Japanese Pacific Empire. In her way stood the might of the Allied navy to which, for the US Navy, much focus was given to broadening the tactical reach of its submarine fleet managed by its well-trained submariners - proving the most fatal occupation in the whole of the war.
The Balao-class family of diesel-electric submarines was part of the growing underwater arm of the USN with construction of these boats beginning in 1942. Manufacture would span into 1946 to which the last vessel would be retired in 1971. Some 128 boats in the class were completed and led by the USS Balao herself with many storied careers and histories born from this submarine family which - next to the preceding Gato-class - were the most important class to the USN scope of operations in the Pacific (the Balao-class was actually built as an improved Gato-class). The end of the war signaled the cancellation of some 63 boats that had been ordered and, of the 117 officially retired, nine of the class went on to see preservation as war memorials.
One boat in the Balao-class was the USS Piranha (SS-389). She was built by the skilled workers of the Portsmouth Naval Shipyard of Kittery, Maine beginning with her keel laid down on June 21st, 1943. She was launched to sea on October 27th of that year and, after passing her requisite sea trials, was commissioned on February 5th, 1944. As part of the Balao-class of attack submarines, the USS Piranha followed the same sleek clean lines with a boat-like bow, tapered stern and contained conning tower. The deck of the class was designed as flat to allow for walking by crew and management of the surface guns. Armament included 10 x 21" (533mm) torpedo tubes of which six were mounted to face forward in the bow and the remaining four set to face the rearwards at the stern. This allowed the vessel to engage targets at front and rear without having to turn the entire vessel around. Surface threats were countered by her 5" (127mm) /25 caliber deck gun which could also be used for offshore bombardment. Aerial threats were countered by 1 x 40mm Bofors and 1 x 20mm Oerlikon anti-aircraft guns. Her crew complement included 10 officers and around 70 enlisted personnel. Watches were kept in shifts to allow for recovery on the extended patrols required of all submarines during the war. Crewmembers were cross-trained when possible and various specialists (cooks, gunners, mechanics, pilots) made up her ranks throughout.
Propulsion was made possible by the configuration consisting of 4 x Fairbanks-Morse Model 38D8-1/3 10-cylinder diesel engines driving electrical generators and coupled to 2 x 126-cell Sargo batteries with 4 x Elliot electric motors. The propulsion system drove a pair of shafts to which, when surfaced, the submarine relied on its diesel engines which outputted 5,400 shaft horsepower and could make 20.25 knots with a displacement of 1,550 tons. When submerged, the boat relied on its battery supply to power the critical system, able to make 8.75 knots with a displacement of 2,500 tons. As with other diesel-electric submarines of the day, the USS Piranha was required to surface to recharge her batteries and oxygen supply (deadly CO2 levels would build up over time and needed to be expelled lest they kill the crew). This meant that the vessel could only remain submerged for up to 48 hours and, when surfaced, she was highly vulnerable to enemy attack by air (primary from diving floatplane and flying boat aircraft) or surface warship. On her diesel engines alone, the Piranha could be kept out at sea for some 75 days total, assuming food supplies were ample. The USS Piranha could reach depths beyond 350 feet (tested down to 400 feet) before hull pressures could take her.
Following many of the boats before her, the USS Piranha set sail for Pearl Harbor, Hawaii by passing Floridian waters en route to the Pacific Ocean via the Panama Canal. She arrived at Pearl on May 18th, 1944 and took on her first war patrol of the war in June working in conjunction with other USN forces. Her primary target became Japanese convoys that were assigned to resupply forward positions to which the USS Piranha sank the Nichiran Maru and the Seattle Maru on July 12th and July 16th respectively. Though attacked by enemy warships and aircraft, the USS Piranha managed to avoid damage and returned to Majuro in the Marshall Islands for resupply.
Reconnoitering then followed throughout September, this assisting the Third Fleet during its successful attack on Peleliu of the Palau Island chain. She struck out on patrol on her own following the assault and faced off with a Japanese Navy patrol craft on October 9th, escaping is depth charge bombardment before returning to Pearl on October 23rd, 1944. She was then assigned to the South China Sea as part of a submarine attack group from November 19th to January 13 , 1945 and also charged with recovering downed air crew during their assault on Kyushu. Despite landing a pair of fish (torpedoes) into a Japanese merchant (not sinking her), the Piranha was forced to retreat due to the presence enemy warships. The USS Piranha made her way to Guam for a needed refit and remained there until February 11th.
Covering a triangle passage between Hong Kong (China), Formosa (modern-day Taiwan) and Luzon (Philippines), the USS Piranha once again operated as part of a coordinated attack group, concentrating on merchant vessels in the area. She successfully engaged a lesser vessel on February 27th and missed out on a large convoy converging on Hong Kong on Match 5th (slowed in her interception by the large presence of civilian fishing boats (her crew actually had fabricated an IJN flag and maneuvered the fishing boats successfully only to have missed the convoy altogether by the time Piranha had passed through).
A Japanese presence on the small island of Prata in the South China Sea allowed Piranha to utilize her deck gun against several before leaving for Midway Island while evading roaming enemy aerial patrols. Piranha was out of action from April 21st to May 17th, eventually entering her next war patrol and undergoing the usual (patrol-recovery-bombardment) service - this time assisting air, land and naval forces at Marcus Island (Minami-Tori-Shima) from May 22nd to May 31st.
By this time, Allied gains were such that the USS Piranha and her kind were consistently operating closer to the Japanese mainland, continuing to target merchant ships and other vessels of opportunity though at the expense of operating far from home and within crowded shallow waters. She claimed a tanker, an oil trawler and a pair of other trawlers while being repeatedly chased and targeted by Japanese hunters. After suffering damage from a depth charge attack, the USS Piranha retreated to the safety of Pearl Harbor, arriving on July 10th, 1945 (the war in Europe had concluded in May through Allied gains and the suicide of Hitler, now leaving all of the Allied war effort to focus solely on the Pacific).
The USS Piranha was re-launched from Pearl Harbor on August 14th and took to her sixth war patrol. The war situation for the Empire of Japan had become exceedingly worse as her naval prowess was neutered while her air power extremely limited. Lack of viable armored fighting vehicles and adequate replacements only served to hurt Japanese war-making capacities. Furthermore, between August 6th and August 9th, the Japanese cities of Hiroshima and Nagasaki fell victim to the power of American atomic bombs which ultimately forced the surrender process (as many as 246,000 people were believed killed in the blasts, not taking into account effects of radiation exposure in the years following). While devastating to the Japanese, the bombs served to spare the lives of the soldiers that would have been required to take the fiercely-defended Japanese mainland in an projected all-out amphibious assault. If the Pacific Theater proved anything to the Allies it was that the Japanese would fight to the last and make life a living hell for the American soldier.
On August 15th, the end of the war against Japan was formally announced with an unconditional surrender. The USS Piranha was recalled to Pearl and made her way back to San Francisco on September 11th, 1945, formally completing her wartime service with the USN. She served in "Operation Magic Carpet", the returning of thousands of veterans stateside for a time. In all, the boat was honored with five Battle Stars for her combat service. She was decommissioned on May31st, 1946 and lay in reserve status. On November 6th, 1962, she was given the new classification of "AGSS-389" and served out the remainder of her days as such until she was officially struck from the Naval Register on March 1st, 1967. She joined many USN vessels in being unceremoniously scrapped, her hull be sold off on August 11th, 1970.
The USS Piranha (SS-389) is the only USN vessel to have been named after the Piranha, a ferocious omnivorous fresh water fish of South America.