Wikipedia:Selected anniversaries/April 9
- 193 - Septimius Severus was proclaimed Roman Emperor.
- 1865 - Confederate General Robert E. Lee surrendered to Union forces.
- 1940 - Operation Weserübung: Germany invaded Denmark and Norway; Occupation of Denmark begins.
- 1959 - NASA announced the selection of the Mercury program astronauts.
- 1991 - Georgia declared independence from the Soviet Union.