That day in 1704:                                    

 

If you, like me, have been doing your homework in readiness for this year’s tercentenary celebrations, you will have noticed an apparently glaring inconsistency in the supposed date of the British capture of Gibraltar. Most official sources and luminaries like General Sir William Jackson offer the 4^th of August as the invasion date; yet people who were there at the time like the Marines, or those who arrived a few decades afterwards, like John Drinkwater, insist on the 23^rd of July. How can this be? The military precision of such writers leaves little room for error, especially in something as fundamental as the date.

 Well, truth is often stranger than fiction and the truth here is; both dates are correct. Before you argue the impossibility of that statement, I had better introduce Christopher Clavius SJ, the Jesuit scientist and mathematician who solved an 800 year old problem and contributed to our historians’ dilemma.

                     

Clavius was employed in the Vatican's flambouyantly named Tower of the Winds, as an astronomer and head mathematician of the Collegio Romano. 

From 45 BC the civilised world had measured time by the Julian calendar which unfortunately had not remained strictly accurate. In 45BC the transit time for the earth around the sun was 365.2422 days - now it is 365.2419 days - and the error had been accumulating year by year. By the sixteenth century, Easter was so late that it was almost summer by the time it was celebrated. Everybody knew what the problem was, but the difficulties of resolving it were almost beyond the mathematics of the time. It was Clavius’ solution, which lead to Pope Gregory XIIIth issuing the Papal Bull Inter Gravissimas in 1582. In that year the Julian calendar ended on the 4^th October to be followed the next day by the start of the Gregorian calendar as Friday the 15^th October. That adjustment of eleven days restored the equilibrium between the solar calendar and the terrestrial calendar used by mankind. Clavius’ calculations were so precise that the next adjustment, the insertion of an additional day, will not be needed until 4317AD.

 Unfortunately, implementation of the Papal Bull was neither an immediate nor a universal success. Some people became disoriented and windows were broken in the houses of some European Jesuits by mobs who believed they had been robbed of eleven days. The Orthodox Church saw it as a Roman intrusion and Protestant countries were unwilling to accept any decree from a pope. In the end, England and her colonies did not accept Clavius’ calendar until 1751 (the Chesterfield Act) and Orthodox Russia not until the Bolshevik revolution.

 All of which helps explain why to the besieged Spaniards their capitulation was on the 4^th August (Gregorian) whilst the victorious Britons knew their attack had succeeded on the 23^rd July (Julian). Both were right, but from their differing perspectives. To those historians closer to the event, the change of calendar - within living memory - was unremarkable; events before the change would use Julian dates and those after it, Gregorian. To later historians the need to compare events across Europe on the same timeline, made the choice of Gregorian dating more convenient; since only England and her colonies were out of step. 

 So there we have it; the apparent date of the capture of our Rock will be largely determined by your choice of historian, but in the end both dates are the same day.          

                                                                           

                                                                                    The Tower of the Winds
  

 

 First published in The Gibraltar Magazine February 2004.        Paul Hodkinson.