Final answer:
William Henry Harrison, nicknamed 'Tippecanoe', was the first president to succumb to the 'Twenty Year Curse', dying a month into his term after being elected in 1840.
Step-by-step explanation:
The "Twenty Year Curse" is associated with a pattern that people noticed regarding U.S. presidents elected in years divisible by 20, starting in 1840 and ending in 1960. This supposed curse was that those presidents often died in office. The first president to succumb to this pattern, nicknamed "Tippecanoe" after his military exploits at the Battle of Tippecanoe, was William Henry Harrison. He was elected in 1840, took office in 1841, and unfortunately passed away from pneumonia a month later, after delivering an inaugural address in harsh weather conditions without proper attire.