1803 followed by 1804
1803 (MDCCCIII) was a common year starting on Saturday of the Gregorian calendar and a common year starting on Thursday of the Julian calendar, the 1803rd year of the Common Era (CE) and Anno Domini (AD) designations, the 803rd  year of the 2nd millennium, the 3rd  year of the 19th century, and the  4th   year of the 1800s decade. As of the start of 1803, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.