1941 animators' strike which lasted five weeks. While a federal mediator from the National Labor Relations Board negotiated with the two sides, Disney accepted an offer from the Office of the Coordinator of Inter-American Affairs to make a goodwill trip to South America, ensuring he was absent during a resolution he knew would be unfavorable to the studio. As a result of the strikeand the financial state of the companyseveral animators left the studio, and Disney's relationship with other members of staff was permanently strained as a result. The strike temporarily interrupted the studio's next production, Dumbo (1941), which Disney produced in a simple and inexpensive manner; the film received a positive reaction from audiences and critics alike. World War II and beyond: 1941–1950 Shortly after the release of Dumbo in October 1941, the U.S. entered World War II. Disney formed the Walt Disney Training Films Unit within the company to produce instruction films for the military such as Four Methods of Flush Riveting and Aircraft Production Methods. Disney also met with Henry Morgenthau Jr., the Secretary of the Treasury, and agreed to produce short Donald Duck cartoons to promote war bonds. Disney also produced several propaganda productions, including shorts such as Der Fuehrer's Facewhich won an Academy Awardand the 1943 feature film Victory Through Air Power. The military films generated only enough revenue to cover costs, and the feature film Bambiwhich had been in production since 1937underperformed on its release in April 1942, and lost $200,000 at the box office. On top of the low earnings from Pinocchio and Fantasia, the company had debts of $4 million with the Bank of America in 1944. At a meeting with Bank of America executives to discuss the future of the company, the bank's chairman and founder, Amadeo Giannini, told his executives, "I've been watching the Disneys' pictures quite closely because I knew we were lending them money far above the financial risk. ... They're good this year, they're good next year, and they're good the year after. ... You have to relax and give them time to market their product." Disney's production of short films decreased in the late 1940s, coinciding with increasing competition in the animation market from Warner Bros. and Metro-Goldwyn-Mayer. Roy Disney, for financial reasons, suggested more combined animation and live-action productions. In 1948, Disney initiated a series of popular live-action nature films, titled True-Life Adventures, with Seal