June 23

Pedro de Mendoza (1487–23 June 1537) led Spain's first expedition to the Río de la Plata region. In 1536, he founded the settlement of Buenos Aires, though it struggled to survive due to conflicts with indigenous peoples and lack of supplies. Mendoza negotiated with local tribes and established trade routes, laying the groundwork for later colonization. Despite his efforts, he fell ill and returned to Spain, dying en route. His expedition opened the way for Spanish dominance in South America and the eventual establishment of modern Argentina.

Born in 1692, Karl Ludwig von Pöllnitz led a life of diplomatic missions, military service, and exploration across Europe. He served at various royal courts, including those of France and Prussia, offering him firsthand views of political intrigue. Pöllnitz documented his experiences in a series of memoirs that blended adventure, scandal, and cultural observation. His works, published in French and later translated, provided readers with an intimate look at 18th-century aristocratic life. He traveled extensively from the Ottoman Empire to the Scandinavian courts, gathering anecdotes and curiosities. Pöllnitz's lively and candid writing style made his memoirs popular throughout Europe. He died in 1775, remembered as one of his era's most engaging travel writers.

Dr. Jerri Nielsen volunteered in 1999 at the Amundsen-Scott South Pole Station as the station physician. During the Antarctic winter, she discovered and biopsied a suspicious breast lump on herself. She improvised chemotherapy protocols with supplies airdropped in midwinter by the U.S. Air National Guard. Her determination and resourcefulness earned international acclaim and inspired the book and film Ice Bound. After returning from Antarctica, she continued her work in remote medicine and cancer research. Her remarkable story remains a testament to medical courage under the harshest conditions. She passed away in 2009, leaving a lasting legacy in polar exploration and healthcare.