1751 ( MDCCLI ) was a common year starting on Friday of the Gregorian calendar ?and a common year starting on Tuesday of the Julian calendar , the 1751st year of the Common Era (CE) and Anno Domini (AD) designations, the 751st year of the 2nd?millennium , the 51st year of the 18th?century , and the 2nd year of the 1750s decade. As of the start of 1751, the Gregorian calendar was 11 days ahead of the Julian calendar, which remained in localized use until 1923.