On this day in 1922, West German police officer Xavier March was born in Hamburg, Germany. March, who before joining the police had been a U-boat commander in the Kriegsmarine and was captured by the Allies near the end of the Second World War, would play a crucial role in foiling a rogue KGB operative's plot to assassinate President Lyndon Johnson during a state visit by Johnson to West Germany in April of 1964 to meet with West German chancellor Konrad Adenauer.

On this day in 1929, the father of future West German police officer Xavier March died of wounds sustained in combat on the Western Front during the First World War, leaving Mrs. March to continue raising her only child alone.

On this day in 1945, Xavier March was finally released from Allied military custody and left Scotland for home; his bunkmate and future police partner Max Jaeger would be released two days later.

On this day in 1939, Xavier March, now seventeen, enlisted in the German navy and began U-boat training.

On this day in 1940, Xavier March was sent to the North Sea as part of the crew of the submarine U-91 to participate in the German campaign against the Allies in Norway.

On this day in 1928, future US Secret Service agent Charlotte Maguire was born in Norfolk, Virginia.

On this day in 1941, Xavier March was promoted to lieutenant and transferred to the submarine U-106 as that vessel was being deployed to the Caribbean following Hitler's declaration of war on the United States after Pearl Harbor.

On this day in 1938, Charlotte Maguire's father Michael, a detective with the Norfolk Police, was shot and killed while foiling a bank holdup attempt downtown.

Years later, Charlotte would confide to West German police officer Xavier March that a subconscious desire to avenge her father's demise was one of her motives for pursuing her own law enforcement career.

On this day in 1947, Xavier March contracted tuberculosis; this illness would keep him confined to a hospital bed in Munich for almost a year. It was right around this time that he met his future wife, Klara Eckart.

On this day in 1943, Xavier March became the youngest U-boat captain in the history of the German navy, assuming command of the U-106 after his old commanding officer was killed during a British depth-charge attack. March's bunkmate, Rudi Halder, assumed March's former post as U-106's executive officer.

On this day in 1944, a then-sixteen year old Charlotte Maguire, constantly quarreling with her widowed mother, was shipped off to a boarding school in Maryland.          

On this day in 1944, U-106 captain Xavier March was captured by a British naval patrol off Iceland and incarcerated at a POW camp in Scotland, where he would spend the final months of the Second World War. During his incarceration he would make the acquaintance of the man who would later become his police partner, Max Jaeger.

On this day in 1946, Xavier March was hospitalized with tuberculosis; he would spend more than a year confined to a Munich hospital, during which time he met his future wife Klara Eckart.

On this day in 1949, Xavier March joined the harbor patrol division of the Wilhelmshaven police.