Short answers, pulled from the story.
San Diego is called the Birthplace of California because it was the first site visited and permanently settled by Europeans on what is now the West Coast of the United States. Gaspar de Portolá established the Presidio of San Diego in May 1769, and Junípero Serra founded Mission San Diego de Alcalá in July of the same year, making it the first European settlement in present-day California.
The Kumeyaay village was called Kosa'aay, meaning "drying out place" in the Kumeyaay language. It was made up of thirty to forty families living in pyramid-shaped housing structures, supported by a freshwater spring. After the Spanish arrived, the Kumeyaay renamed the town Tepacul Watai, meaning "Stacked Big".
Operation Cherry Blossoms at Night was a Japanese military plan during World War II to use kamikaze planes carrying fleas infected with plague to attack civilian population centers in San Diego. The plan was scheduled to launch on the 22nd of September 1945. Japan surrendered five weeks earlier, preventing the attack from being carried out.
Juan Rodriguez Cabrillo claimed the bay for the Spanish Empire in 1542, sailing his flagship San Salvador from Navidad, New Spain. He named the site San Miguel. The name San Diego was given later by Sebastián Vizcaíno, who surveyed the harbor in November 1602 and named it after the Catholic Saint Didacus.
The San Ysidro Port of Entry is the busiest international land border crossing in the world outside Asia, and ranks fourth overall. San Diego shares a 15-mile border with Mexico and is authorized to operate as a foreign-trade zone. Together with Tijuana, San Diego forms the second-most populous transborder metropolitan area in the Western Hemisphere, home to an estimated five million people as of 2022.
The military is the largest single employer in San Diego, with Naval Base San Diego alone employing 40,472 people according to the city's 2024 report. The military accounts for roughly 25 percent of the city's GDP and 23 percent of total jobs in San Diego County. In 2008, the naval fleet comprised 53 ships and more than 35,000 sailors, marines, and civilians, and the city hosts the largest naval fleet in the world.