| Year | Date | Historical Events |
| 1916 | Aug 29 | Contract awarded to the Fore River Shipbuilding Co., Quincy, MA. |
| 1918 | Mar 28 | Keel laid down at the Fore River Shipbuilding Co.,Quincy, MA. |
| 1919 | Aug 15 | Launched. |
| | Sep 23 | Commissioned at Boston, MA. with LT. F. J. Cunneen in command.
|
| 1920 | Mar 11 | R-12 transited to New London,CT. |
| | Jun 30 | R-12 transited the Panama Canal. |
| | Jul 10 | R-12 arrived at San Pedro,CA. |
| | Aug 30 | R-12 departed the California coast for Pearl Harbor, HI. |
| | Sep 6 | R-12 arrived at Pearl Harbor, HI. |
| 1930 | Dec 12 | R-12 got underway for the East coast. |
| 1931 | Feb 9 | R-12 arrived at New London,CT. |
| 1932 | Sep 27 | Departed New London for Philadelphia,PA. |
| | Dec 7 | R-12 was placed in the Reserve Fleet in Philadelphia,PA. |
| 1940 | Jul 1 | R-12 shifted to New London,CT. for re-commissioning |
| | Oct 16 | R-12 was re-commissioned at New London,CT. |
| | Dec 10 | R-12 sailed for Panama. |
| | Dec 23 | R-12 arrived at Panama. |
| 1941 | Oct 31 | R-12 returned to New London,CT. |
| 1942 | Feb 1 | R-12 commenced patrols to the South and for the next year operated primarily from Guantanamo Bay, Cuba and Key West, FL. |
| 1943 | Mar 1 | R-12 returned to New London,CT. |
| | May 1 | R-12 returned to Key West, FL. where she trained submariners for the remainder of her career.
|
| | Jun 12 | R-12 was lost while making preparations for a torpedo practice, when the Forward Battery compartment flooded. 42 men were lost. 6 survived. |
| | Jul 6 | Struck from the Naval Register. |