1. On March 18, 1837, the Republic of Texas officially adopted its first flag, known as the "Lone Star Flag." The flag featured a single, five-pointed star on a field of blue, symbolizing Texas's independence and sovereignty.

2. March 18, 1836, marks the day that Mexican General Santa Anna arrived with his army to begin the siege of the Alamo in San Antonio. The 13-day battle that followed resulted in the deaths of nearly all of the defending Texan forces, including renowned individuals like Davy Crockett and Jim Bowie.

3. On March 18, 1891, philanthropist and oilman William Marsh Rice founded Rice Institute (now Rice University) in Houston, Texas. Rice's vision was to create a world-class research university in the heart of Texas, and today Rice is consistently ranked among the top 20 universities in the country.

4. One of the deadliest school disasters in American history occurred on March 18, 1937, when a natural gas explosion destroyed the New London School in New London, Texas, killing more than 300 students and teachers. The tragedy sparked nationwide public outrage and led to significant changes in school building safety regulations.

5. March 18, 1962, is notable for being the day that astronaut John Glenn visited San Antonio to receive a hero's welcome after becoming the first American to orbit the earth. Glenn's historic flight on February 20, 1962, made him an instant celebrity and national hero.