He spent four years as commander of the Reserve Officers Training Corps (ROTC) detachment at the Colorado School of Mines, his Alma mater, and served in a U.S.-based psychological warfare unit during the Korean War.

[8] Fertig was described as "tall, sandy-haired with an athletic build" and "being calm, genial, deliberate and possessing a remarkable memory and a great facility for remembering names.

Later, after organizing the guerrilla forces on Mindanao, he wrote in this diary, I am called on to lead a resistance movement against an implacable enemy under conditions that make victory barely possible even under the best circumstances.

Upon learning that Sharp had surrendered his forces to the Japanese on May 10, 1942,[5] Fertig then spent more weeks considering his options, realizing that to gain authority, he had to wait until guerrillas contacted him.

[19][20] Many of the emerging guerrilla forces at that time were bandit groups pretending to fight the Japanese, but using the collapse of the American-supported government to set themselves up as rulers of local areas.

[21][22] On September 12, 1942,[23] the leader of one strong group approached Fertig, hoping to use him as a front (i.e. representing American military forces) to assume authority over the entire island.

[25] Believing that he needed a higher rank, so he would be taken seriously by potential recruits to his struggle, including the leaders of other existing guerrilla bands, Fertig promoted himself to brigadier general.

[28] Japanese bombings, destruction by retreating American troops, deprivations by bandit guerrilla bands, and hoarding by civilians had reduced available war supplies, as well as those items necessary to run an effective government.

For example, tuba was brewed from coconut palms to provide alcohol to fuel gasoline vehicles, batteries were recharged by soaking them in tuba, soda bottles and fence wire were used to create a telegraph to enhance communications, curtain rods were cut into pieces and shaped to provide ammunition for .30 caliber rifles, steel was shaved from automobile springs and curled to make recoiling springs for rifles, money was printed in both English and the local language using wooden blocks, and fishermen towed Japanese mines ashore to secure the explosive amatol so it could be used to make gunpowder.

[23][40] Due to the difficulty in communicating with Fertig and his command via makeshift radio Almendres had built, a submarine loaded with military and medical supplies was sent to Mindanao, arriving on March 5, 1943.

One was Charles Smith,[5] who on December 4, 1942,[42] had escaped with two other Americans and two Filipinos by sailing a small boat to Australia, perhaps, at that time, the longest open-boat voyage since Captain Bligh's.

[45] Their role, as Smith and Parsons explained to Fertig, was to verify that he was actually leading a resistance movement and, if so, whether it was worth the risk of men and supplies to support him.

These traits sometimes led to clashes with the older men who had lived in the Philippines for years and were now in command positions due to their reserve commissions or promotion by Fertig.

Over the next two and a half years, Fertig created and commanded the Mindanao segment of the "United States Forces in the Philippines" (USFIP), recruiting escaped prisoners-of-war, and soldiers and American civilians who had refused to surrender.

The American South West Pacific Area command wanted Fertig to form coastwatcher units to report on Japanese movements, especially shipping, as its main effort.

[72] Another ship, called The Bastard, was actually a 26-foot (7.9 m) whaleboat captained by Australian Robert "Jock" McLaren, an escaped prisoner-of-war from the Sandakan POW camp on Borneo.

McLaren would sail his boat into Japanese controlled ports in broad daylight, shoot up the supply vessels and piers with machine guns and a mortar, then turn tail and run.

For the 10th Military District, commanded by Fertig, he had this to say: We did have considerable information about dispositions of enemy troops, since guerrilla forces on Mindanao were the most effective and best organized in the Philippines.

[79] However, probably the best estimate of the value of guerrilla intelligence came from the Japanese, when they released an official communique stating that the Americans had "perfected a new aerial bomb which was attracted by concentrations of ammunition and fuel."

When the submarine USS Narwhal arrived at Mindanao in Nov. 1943 to deliver supplies, the crew was met by a uniformed band playing "Stars and Stripes Forever.

In addition, USS Narwhal had the room to evacuate guerrillas needing critical medical care, as well as American civilians, primarily women and children, who had been hiding out in the Philippines and were suffering from malnutrition and diseases.

[28] As an indicator of USFIP strength on Mindanao, during January and February 1945, in preparation for the return of regular American forces, the guerrillas seized the Dipolog airstrip in northern Zamboanga and held it while surrounded by the Japanese.

McClish and Childress were among several American officers serving under Fertig who requested transfers from the guerrillas to regular U.S. army commands which became possible after the U.S. invasion of the Philippines on October 20, 1944.

[98] Robert Lapham, another guerrilla leader, described McClish and Childress's opinion of Fertig as "paranoid and consumed with personal ambition, not to speak of ungrateful and discourteous to them after they had made it possible for him to move his headquarters to a safe location.

Undiplomatic and belligerent, he was condescending toward all Filipinos, except those who, like himself, had substantial investments in the Philippines... and by the time MacArthur was ready to land on Leyte, Whitney had converted most of the staff to reactionaryism.

The citation reads in part:[66] Constantly engaged with vastly superior enemy forces, he engendered Filipino faith and confidence in their ultimate deliverance, instilled in them the will to resist, and united them in the cause of freedom.

Colonel Fertig was released from active duty in 1956 after serving as deputy director of the joint staff for the provisional military assistance advisory group in South Korea from 1954 to 1955.

As numerous small craft full of shouting men surrounded the ship, Wendell and Mary Fertig saw:[107] ...thousands of Filipinos waiting at the waterfront at Cagayan...

The men were shouting and the women were singing...They then saw a huge banner over the pier:[9] Welcome the Indomitable Patriot Who Have Lessened Human Suffering on Mindanao Wendell Fertig ran a successful mining company in Colorado until he died on March 24, 1975[1] at the Lutheran Hospital in Wheat Ridge.

[109] As of 2021, the Fertig film has not materialized, but in Quentin Tarantino's novelization of Once Upon a Time in Hollywood the backstory of Pitt's Cliff Booth character is revealed to be that of an American World War II commando who was captured and imprisoned by the Japanese in the Philippines, but escaped into the jungle and went on to wage guerrilla war against occupying Japanese forces alongside his "Filipino guerrilla brothers.