1. On April 23, 1631, a Dutch ship called De Walvis arrived in the Delaware Bay, becoming the first European vessel to explore the region that would later become Delaware.

2. On April 23, 1781, the American Revolutionary War Battle of Petersburg took place in Somerset County, Maryland, just across the Delaware border. The battle was a strategic victory for the Continental Army, which had been struggling to contain the British army in Virginia.

3. On April 23, 1813, the Delaware General Assembly created the state's first public school system. This marked a major milestone in the state's efforts to expand educational opportunities for its citizens.

4. On April 23, 1910, the city of Wilmington opened its new Electric Theater, which was one of the first movie theaters in the state to offer air conditioning.

5. On April 23, 1973, the Delaware Supreme Court issued a landmark ruling in the case of Roe v. Wade, which established a woman's right to terminate a pregnancy under certain circumstances. The ruling remains one of the most significant legal decisions in American history.