The story of Fleet Radio Unit Melbourne (FRUMEL) started in Olongapo, Philippines. In late 1929, the U.S. Navy opened an intercept station at a small Naval base at Olongapo in the Philippines on Subic Bay, facing the South China Sea.  The site (Station C) was officially opened in July, 1930.
Unfortunately, Station C personnel were delayed by having to assume primary responsibility for all regular Navy communications in and out of the base at Olongapo.  As a result, they did not start intercepting communications until August 1932, as Station C (CAST).  Station C was destined to move to the below locations in ten years in an attempt to find secure operating spaces, living quarters and antenna sites where Japanese Navy signals could be heard consistently.
  •    Olongapo, 1930-35
  •    Mariveles, 1935-36
  •    Cavite, 1936-40
  •    Corregidor, 1940-42
  •    Melbourne, 1942-45

Station C was transferred from Olongapo to Mariveles and then to the Navy Yard in Cavite. In mid-October 1940, Station C would finally establish itself in a special tunnel built for the Navy at Monkey Point on Corregidor.  Two months later, Station C absorbed the mission and the personnel of Station Able in Shanghai, China, which was closed.

The Battle for Corregidor
On December 29, 1941, the defenders got their first taste of aerial bombardment on Corregidor.  The attack lasted for two hours as the Japanese destroyed or damaged the hospital, Topside and Bottomside barracks, the Navy fuel depot and the officers club. Three days later, the island garrison was bombed for more than three hours.  Periodic bombing continued over the next four days and with only two more raids for the rest of January, the defenders had a chance to improve their positions considerably.  To the amusement of the beach defenders on Corregidor, the Japanese dropped only propaganda leaflets on January 29.  On March 12, 1942, under cover of darkness, General MacArthur was evacuated from Corregidor on four PT boats for Mindanao, where he was eventually flown to Australia.
Henceforth from December 29, 1941, to the end of April 1942, despite incessant Japanese aerial, naval and artillery bombardment, the garrison on Corregidor, consisting mainly of the 4th Marine Regiment and combined units from U.S. Navy, Army units and Filipino soldiers, resisted valiantly, inflicting heavy enemy losses in men and planes.  The defenders were living on about thirty ounces of food per day.  Drinking water was distributed only twice per day, but the constant bombing and shelling often interrupted the ration. When the bombardment killed the mules in the Cavalry, they would drag the carcasses down to the mess hall and cook them.  The continued lack of proper diet created problems for the Corregidor garrison, as men grew weak and lacked reliable night vision.  From Cebu, seven private maritime ships under orders from the army, loaded with food supply, sailed towards Corregidor.  Of the seven ships, only one was able to reach Corregidor, the MV Princessa commanded by 3rd Lt. Zosimo Cruz.
Evacuation of the Cryptologists
When Japanese troops overran the Bataan Peninsula and threatened Corregidor, Admiral Ernest King, Commander in Chief U.S. Fleet/Chief of Naval Operations ordered the radio intelligence personnel (CT) off Corregidor via submarines on April 8, 1942 to prevent their capture by the Japanese.  The knowledge these individuals had about Japanese communication, codes, ciphers, etc., if captured, would have a devastating effect on the intelligence efforts of the U.S. Navy.  Before evacuating Corregidor, however, the CTs burned all intelligence records and reportedly destroyed their Purple machine by throwing it into Manila Bay.  After their evacuation, the CTs moved to Melbourne Australia and linked up with codebreakers on the Royal Australian Navy. The unit became Fleet Radio Unit Melbourne, (FRUMEL).  FRUMEL closed on November 1, 1945.
However, one CT was not evacuated.  Chief Commissary man (ship’s cook) Arthur R. Thompson was assigned as cook for the CT detachment on the island.  Since he had no knowledge of the duties the intelligence personnel were accomplishing, he was left behind.  He survived the Japanese Death march and imprisonment in Mongolia.  After the war he wrote a letter to LT John Litewiler (the officer in charge of the CTs on Corregidor 1941-1942) to let him know that there was Japanese spy on Corregidor before the war.  When the Japanese came aboard the island, they had not only names, but also pictures of the CT personnel.  And he added, they (the Japanese) were quit unhappy about not capturing them.
Unrelenting bombing and shelling
Japanese bombing and shelling continued with unrelenting ferocity.  Japanese aircraft flew 614 missions dropping 1,701 bombs totaling some 365 tons of explosive.  Joining the aerial bombardment were nine 240 mm howitzers, thirty-four 149 mm howitzers, and 32 other artillery pieces, which pounded Corregidor day and night.  It was estimated that on May 4 alone, more than 16,000 shells hit Corregidor.  From April 28, a concentrated aerial bombardment by the 22nd Air Brigade, supported by ground artillery on Bataan from May 1 to May 5, 1942, preceded landing operations.
Final assault on Corregidor
On May 5, Japanese forces boarded landing craft and barges and headed for the final assault on Corregidor. Shortly before midnight, intense shelling pounded the beaches between North Point and Cavalry Point.  The initial landing of 790 Japanese soldiers quickly bogged down from surprisingly fierce resistance from the American and Filipino defenders whose 37 mm artillery tolled heavily on the landing fleet.  The Japanese struggled because of the strong sea currents between Bataan and Corregidor and from the layers of oil that covered the beaches from ships sunk earlier in the siege, and they experienced great difficulty in landing personnel and equipment.  However, the overwhelming number of Japanese infantry equipped with 50 mm heavy grenade dischargers (“knee mortars”) forced the defenders to pull back from the beach.
The second battalions of 785 Japanese soldiers were not as successful. The invasion force did not prepare for the strong current in the channel between Bataan and Corregidor.  This battalion landed east of North Point where the defensive positions of the 4th Marines were stronger.  Most of the Japanese officers were killed early in the landing, and the huddled survivors were hit with hand grenades, machine guns, and rifle fire.  Some of the landing craft did however make it to the location of the first invasion force and found themselves moving inland enough to capture Denver Battery by 1:30 a.m. on May 6.  A counterattack was initiated to move the Japanese off of Denver Battery.  This was the location of the heaviest fighting between the opposing forces, practically face to face.  A few reinforcements did make their way to the frontline 4th Marines, but the battle became a duel of obsolete World War I grenades versus the accurate Japanese knee mortars.  Without additional reinforcements, the battle would quickly go against the defenders.
By 4:30 a.m. Colonel Howard committed his last reserves, some 500 Marines, sailors and soldiers of the 4th Battalion.  These reserves tried to get to the battle as quickly as possible, but several Japanese snipers had slipped behind the front lines to make movement very costly.  An additional 880 reinforcements for the Japanese arrived at 5:30 a.m.  The 4th Marines were holding their positions at the same time losing ground in other areas.  The Japanese were facing problems of their own: several ammunition crates never made the landing.  Several attacks and counterattacks were fought with bayonets.
Surrender of Corregidor
The final blow to the defenders came about 9:30 a.m. when three Japanese tanks landed and went into action.  The men around Denver Battery withdrew to the ruins of a concrete trench a few yards away from the entrance to Malinta tunnel, just as Japanese artillery delivered a heavy barrage.  Particularly fearful of the dire consequences should the Japanese capture the tunnel, where lay 1,000 helpless wounded men, and realizing that the defenses outside Malinta tunnel could not hold out much longer, and expecting further Japanese landings that night, General Wainwright decided to sacrifice one more day of freedom in exchange for several thousand lives.  In a radio message to President Franklin Roosevelt, Wainwright said, “There is a limit of human endurance, and that point has long been passed.”  Colonel Howard burned the 4th Regiment’s and national colors to prevent their capture by the enemy.  Lt. General Jonathan Wainwright finally surrendered the Corregidor garrison at about 1:30 p.m. on May 6, 1942, with two officers sent forward with a white flag to carry his surrender message to the Japanese.
The Japanese losses sustained from January 1 to April 30 and from the initial assault landings from May 5 to May 6, resulted in losses of about 900 dead and 1,200 wounded, while the defenders suffered 800 dead and 1,000 wounded.  Corregidor’s defeat marked the fall of the Philippines and Asia, but Imperial Japan’s timetable for the conquest of Australia and the rest of the Pacific was severely upset, and her advance was ultimately checked at the battles for New Guinea, to the turning point in the Pacific War at Guadalcanal.  About 4,000 of the 11,000 American and Filipino prisoners of war from Corregidor were marched through the streets of Manila to incarceration at Fort Santiago and Bilibid Prison, criminal detention centers turned POW camps.  The rest were sent off in trains to various Japanese prison camps.  General Wainwright was incarcerated in Manchuria.  Over the course of the war, thousands were shipped to the Japanese mainland as slave labor.  Some were eventually freed at Cabanatuan and during the battle for Manila’s liberation.
Edited by Mario Vulcano