1. The Battle of Bloody Lane, also known as the Battle of Antietam, was fought on September 17, 1862, but July 27 marks the beginning of the Confederate invasion of Maryland leading up to the battle. Confederate General Robert E. Lee crossed the Potomac River with his army, hoping to draw Union troops away from Virginia and win a decisive victory on Northern soil.

2. On July 27, 1941, the United States Navy established a base at Solomon's Island in Southern Maryland. The base, known as the Naval Air Station Patuxent River, became a major center for naval aviation research and development, and its current mission includes testing and evaluating aircraft and weapons systems.

3. The Baltimore and Ohio Railroad, which played a crucial role in the development of transportation and commerce in Maryland, was chartered on July 27, 1827. The railroad's first section, from Baltimore to Ellicott City, opened for business in 1830 and became the oldest continuously operated railroad in the United States.

4. On July 27, 1921, the Maryland State Police was established as a statewide law enforcement agency. The State Police has since grown to over 1,700 troopers and civilian personnel, and provides public safety and traffic enforcement services throughout Maryland.

5. The first recorded game of baseball in Maryland was played on July 27, 1858, in Baltimore's Madison Square. The game was between the Chesapeake Club and the Excelsior Club, and it was reported in the Baltimore Clipper newspaper. Baseball quickly became a popular sport in Maryland, and the state has produced many notable players and teams over the years.