On February 9, 1939, he graduated from the Army's Off Shore Patrol (OSP) Training School & Headquarters in Muelle del Codo, Port Area, Manila as part of the newly formed maritime element which he voluntarily joined.
Liwanag was one of nine allied foreign naval officers which included countries from France, Taiwan, Japan, Turkey, Spain, Norway, Greece and Germany.
Four days later, the Japanese planes bombed the Offshore Patrol two-storied headquarters in Muelle del Codo, Port Area, Manila where he was stationed;[2] he was in Bataan when this incident happened.
Since the military wasn't returning to Manila, the OSP Commander, Captain Enrique L. "Henry" Jurado, ordered the Headquarters to be burned down completely before the Japanese arrival into the city.
When the sea duty unit is not transferring vital supplies, they were to engage the Japanese forces using their Q-boats by hindering or destroying any landing assaults on the country's shoreline.
During a cargo drop-off, Liwanag noticed a small number of armed and unarmed soldiers, about a dozen, were trying to board the docked Q-boats which was strictly ordered to carry ammo and supplies only, not indigenous personnel.
As he returned from the supply trip back to Lamao, his harbor and shoreline was overwhelmed by a larger crowded chaotic scene of desperate troops eager to escape the Japanese advance.
Then he organized the harbor evacuations because the retreating troops were endangering the Q-boats by overloading and capsizing them, at the same time restore some form of order to the chaotic mess.
He ordered a number of these troops to create a guard perimeter, which a group of volunteers took the task to provide a security buffer outside the dock facilities from enemy incursions while the evacuation took place.
[1] When all the troops and non-essential personnel were safely shuttled off, he ordered all remaining boats to start loading the full fuel canisters on board to be dropped off at a friendly port.
The harbor's total destruction took place late during the night with their withdrawal punctuated by a tremendous explosions of the oil refinery tanks which was seen across the Manila Bay.
Before they turned themselves over to the Japanese, he ordered the immediate destruction of their civilian boats once they docked, which some burned from lighting the portable fuel tanks and later shot out the bottoms to sink them making them less salvageable.
He was transferred by trucks along with his unit to San Fernando, Pampanga, then crammed to standing room in train box cars as the Japanese overloaded them to more than double its capacity to Capas, Tarlac.
The Japanese occupying force released a small number of Philippine military personnel after going thru a "rejuvenation program" to return to civilian life, of which he was one of the fortunate few.
During the fierce month long battle for the capital, he witnessed the brutalities the Japanese troops had inflicted on the Filipino civilian population which was known as the Manila massacre.
After the Japanese were removed from Manila, Liwanag and surviving USAFFE OSP officers were in charge in rebuilding the Offshore Patrol Unit to continue with their duties of securing the country's sea and shores.
The PEFTOK was the 8th foreign country after the Americans and the 27th British Commonwealth Infantry Brigade (consisting of units from the UK, Canada, Australia, New Zealand, India and 2 battalions from Hong Kong.)
After explaining directly to the American HQ commanders of the 10th situation, they gave him free rein in the division's supply depot and motor pool to take whatever Major Liwanag needed.
That flank was covered by Heavy Weapons Company, which was overwhelmed by the shear numbers of enemy pouring into their positions that their machine guns were overheating to melt their barrels.
Outnumbered, the counterattack surprised the Chinese which succeed in Heavy Weapon Company driving them off the hill top, but Captain Yap was mortally wounded by machine gun fire.
Lt. Artiaga was posthumously awarded the Distinguished Service Cross for leading his extremely outnumbered men in the most intense account of the Yultong battle.
It read in part: Applying his keen judgment and professional experience, Commander Liwanag formulated plans for the logistical support and efficient integration of Philippine forces into the Korean War.
According to Lt. Gen Alfonso Arellano, AFP Chief of Staff (1956–1957), he hailed the designation of Liwanag, pointing out that it was the first time that a Filipino officer was chosen to head a vital and big military exercise in which a foreign contingent was participating.
Fifty-six PN officers and three hundred enlisted men had a two-week classroom instruction course on harbor defense to be followed by another two weeks of practical training under competent Filipino and American instructors from Cavite Navy Yard and US Naval Base Subic Bay.
The exercise involved fifteen US and Philippine naval vessels: the US Navy provided picket boats, minesweepers - Fortify, Inflict and Engage, a submarine - USS Capitaine (SS-336), aircraft - namely two Martin PBM patrol bombers, several amphibious vehicles (LVT-4) and harbor defense units.
The Philippine Air Force provided four squadrons consisting of eight P-51 Mustangs, four F-86 Sabre jets, four HU-16 Albatross amphibious flying boats and helicopter rescue teams.
On the morning of January 4, 2011, a newly upgraded patrol gunboat BRP Emilio Liwanag (PG-118) is the latest addition to join the Philippine Navy's floating inventory.
Armored plates were added to the ship's Bridge windows in 2019 as it patrols coastal area of Mindanao as part of the PN Littoral Combat Force.
[37] PC-118 was retired alongside BRP Salvador Abcede (PC-114) as the last of the two remaining Tomas Batilo class to be struck off the Philippine Navy ship register.
[38][39] Decommission ceremony was attended by the ship's officers and crew along with two members of the Liwanag family which took place at Navy Headquarters, Heracleo Alano Naval Base in Sangley Point, Cavite City.