James Koerber was born on November 1, 1922, in Detroit, Michigan. Koerber, the last of a long line of brewmasters, spent the early years of his life with his family producing family label Friars Ale in Iona, Michigan. Shortly after Pearl Harbor, Koerber answered the call to arms and joined the Army Air Corp. For the better part of the next two years, Koerber trained in the United States, England, and Scotland to fly fighter aircraft and was awarded his 'wings' on February 8, 1944.T,raining was a grueling ordeal. After two months of preparatory Pre-Flight training, those with demonstrated ability where sent to Primary Training with the twin wing Steerman aircraft, where they received their first instruction in solo flying. Following this 'trying out' phase, new pilots were sent to Basic Flight Training in Georgia where they flew their first combat-aircraft, the PT-13 "Vibrator." Following Basic Flight, pilots were broken into two classifications for their advanced training: multi-engine bomber flying, or single engine fighter. Koerber elected the latter, which he identified as the more popular, because of the freedom and sheer power of the fighter aircrafts, but was nearly denied admittance to the program. At six foot one inch tall, Koerber was several inches over the maximun height limit for a fighter pilot, a statistic pointed out by a shorter pilot wishing his slot in fighter , school. But after a run in with a sympathetic medic, who asked whimsically "can't you bend your knees?" when on the scale, which made him five foot eleven, Koerber was off to advanced fighter pilot training in Alabama, where he flew the AT-6 and P-40 aircraft.

After training, Koerber was assigned to the 8th Air Corp, stationed at Wattisham, England, and began to dig into the daily life of a pilot. It was hardly glamorous. After a roll call at five in the morning and briefing, pilots finally arrived for breakfast just behind the "groundpounders," or land-side service and administration personnel who did not receive their level of briefing, and likely ended up at the back of the line. Fighter missions could be slotted at virtually any time after that, but involved a fairly predictable routine. After take off from the dispersal area, a pilot then had to make contact with the rest of the group, or the aircraft which had taken off before him. Missions for fighters typically involved providing cover for heavy strategic bombing aircraft, fighting at close range with other fighters, or 'strafing' ground targets. Before entering a combat situation, a pilot first fired a burst from the Mustang's 50 caliber guns to "clear the throat" and ensure that his weapons were in working order - occasionally with poor results. Sometimes the test failed; during others the empty shells hit neighboring aircraft in the formation and when multiple nationalities were involved, such racket could be considered an attack, as happened to a Russian aircraft over Munich assumed to be attacking. This particular incident, though not directly involving Koerber himself; nevertheless grounded his squadron for the last three months of World War II.

Koerber himself had an additional task to perform besides basic assault and support. His plane was equipped with a K-25 camera which could be used to capture reconnaissance data for the Corp command staff. At an order from "Colgate," or the 8th Army Command, Koerber would answer as "Lakeside Camera" to group commander "Lakeside Highway" and swing low for close photographs, provided he had ample "elbow room," or fuel in the Mustang's five hundred gallon tanks, remaining after an engagement to do so. Either way, a pilot would have ample time to explain his actions in the daily mission debriefing before he was allowed to again race the ground pounders for his evening meal. When not on active duty, Koerber was allowed to take his P-51 on leave and travel across Allied territory with ease. In this manner, Koerber was able to track down his brother Clarence, a pilot in the 7th Army Air Corp who was flying from coded locations providing support for General George Patton's army advancing through France.

Koerber's P-5l Mustang had a story in its own right. Koerber had originally been slotted to receive a used P-5l nicknamed the "Rough Hustle" from squad Captain Pickering. However, just before Picker was due to step away from active duty, the Rough Hustle was shot down while in the care of a Captain Muller, while on the way back to Wattisham Muller survived the engagement and escaped to Allied lines, but was forced to bail out of the aircraft. This procedure was complex in its own right. Pilots wore a "G Suit" over their uniforms designed to insulate them against the extreme cold of high altitude flying. This garment was bulking and limited movement, making any jumps even riskier than normal. Moreover, pilots flew with a 45 Colt 1911 automatic pistol in a holster beneath their left arms, an equal hindrance and as much a danger to be captured with behind enemy lines as an asset. In the event of parachuting, pilots were given an "Escape Kit" with highly detailed silk-screened maps of France and Germany, 'button hole' compasses, high energy bars and fishing tackle, razor, and small self-photos for possible identification paper forgery, to help them make their way to Allied lines. In the event that they were shot down over Russian territory, pilots were also given American flags and instructions to shout "Ya Amerikanets," or "I am American" as they parachuted to the ground in the hopes of avoiding Russian fire. With Captain Muller drifting slowly back to the British soil, Koerber would need a replacement aircraft in short order and was accordingly issued the next P-51 to go into service. He named his airplane the Betty Jean, after his wife.

The P-5l was arguable the finest aircraft fielded by the Allies in World War II, but it was hardly the premier fighter of the war. Koerber detailed several encounters with Germany's newest weapons of war: the Messerschmitt ME-262 and the Vengeance Rockets. Against the V-Rockets there was little a fighter could do, as such weapons literally entered the stratosphere before dropping silently upon their land-based target hundreds of miles away. But the Messerschmitt was different. This experimental jet fighter outstripped the Mustang in both range and speed and downed more than a hundred allied aircraft in the war. Fortunately, Germany failed to produce any of these weapons in mass quantities.