In March of 1941, the Ranger and her crew returned to their base in Norfolk, VA after a mission escorting British Lend Lease ships in the Atlantic. Christman, Rector and Hill were met my a man named Rutledge Irvine, who presented them with a very intriguing proposal. He was recruiting pilots for a covert mission in Burma. Sensing an opportunity at real adventure, the trio signed up.
By mid-summer the three pilots were discharged from the Navy, sent to San Francisco and then on to Burma, with passage on a ship called the Bloemfontein. Christman had told his family that he suspected that war with Japan was imminent, and that they should prepare themselves for hostilities in the near future. He said that volunteering was his opportunity to do something of real meaning for the future.
In a Fort Collins Express-Courier article, his brother-in-law, Al Schroeder, recalled Bert saying that "the people of the United States do not know the meaning of patriotism yet, but they will eventually as it takes a severe shock to tell them."
Upon arrival in Burma, he began to keep an illustrated diary of daily events, that the called "Logan's Log". He also created caricatures of the pilots in his Second Pursuit Squadron, incorporating the "Panda Bear" theme. Several of these he managed to paint on the fuselages of the pilot's planes, but his work remained unfinished as the AVG began the defense of Rangoon.
On December 11th, Christman and Rector were chosen to escort a photo plane for a long-range reconnaissance mission over Bangkok, Thailand and its Dong Moung airfield. The mission was a success, but it revealed a massive buildup of Japanese aircraft--poised to attack Burma. Bert and the rest of the Panda Bear squadron were initially sent to Kunming while the "Hell's Angels" remained to defend Rangoon, but his squadron was soon called into action.
Christman arrived with the rest of his squadron at the Mingaladon airfield, north of Rangoon, on December 30, 1941. On January 4th Bert was shot down, his plane riddled with bullets he was forced to parachute to safety. On of the rounds had traveled through his cockpit and grazed his neck; he was hospitalized briefly before returning to duty.
On January 20th he returned from another mission with a badly damaged aircraft.
On Friday, January 23, 1942, 72 Japanese aircraft attacked Rangoon. Christman was one of the 18 planes that were launched to intercept them. He would never return. Christman's plane had come under fire hand been hit in the engine. He was forced to bail out once more. This time, however, as he hung in his parachute and decended to the ground, a Japanese pilot strafed him. Bert was hit in several places and probably died as a bullet passed through the back of his neck. He was buried the next day at the church of Edward The Martyr in Rangoon. His remains were returned to Fort Collins after the war, where he was laid to rest on Saturday, February 4, 1950.