1851 (MDCCCLI) was a common year starting on Wednesday of the Gregorian calendar and a common year starting on Monday of the Julian calendar, the 1851st year of the Common Era (CE) and Anno Domini (AD) designations, the 851st year of the 2nd millennium, the 51st year of the 19th century, and the 2nd year of the 1850s decade. As of the start of 1851, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.
