How should historians compare conflicting dates?

What sources date

First establish whether two dates concern the same event and use the same dating convention. Nottingham’s archival skills unit demonstrates how familiar day-and-month dates can mislead when the year begins at a different point. Investigate a discrepancy before labelling it either a factual error or an alternative notation.[3]

Sometimes the disagreement concerns the event itself. The National Book Trust’s R. K. Tandon volume states that Bhagat Singh was born on 28 September 1907. Its opening chapter presents this within a narrative of his family’s release from imprisonment. The book is a later educational account, rather than a reproduction of a birth register. Identifying its genre is part of evaluating the date, not a reason to ignore it.[1]

By contrast, a Ministry of Home Affairs feature published by the Press Information Bureau on 23 March 2007 states 27 September 1907 as Bhagat Singh’s birth date.[2]

Demonstrate a conversion rather than guessing one

Nottingham offers a different, explicitly British example: a document dated 25 January 1748 under the civil year could belong to January 1749 when the year is reckoned from 1 January. Its guide recommends the form 1748/9 to retain the relationship. This is an explained convention, supported by a stated year boundary. It is not evidence that the two Bhagat Singh dates result from a calendar conversion, and no such explanation is established here.[3]

Trace the evidence behind a repeated date

Tandon’s preface names newspapers and government publications among its materials and says references were checked, but that general statement does not reproduce a particular birth record beside this claim. A next step would be to identify the earliest surviving evidence used for the birthday and compare how later authors transmitted it. Repetition across websites would not create multiple independent witnesses if they all copied the same account. In the absence of that investigation, preserve an attributed alternative rather than silently selecting a date.[1]

For a converted date, retain the original wording and explain the reckoning. Nottingham’s examples distinguish an identified convention from an unresolved factual dispute. Readers should be able to tell whether a date was transcribed, converted, approximately inferred or chosen between competing records. Each operation has a different evidential basis.[3]