| 1863: | Union gunboats pass Confederate batteries at Vicksburg |
| 1924: | Navy commences relief operations in Mississippi Valley floods, lasting until 16 June |
| 1947: | Act of Congress gives Navy Nurse Corps members commissioned rank |
| 1959: | Helicopters from USS Edisto begin rescue operations in Montevideo, Uruguay. By 26 April they had carried 277 flood victims to safety. |