I was recently reading Dušan Uhlír’s book The Battle of the Three Emperors and I came across an intriguing fact about the battle of Austerlitz which took place on the 2th December 1805 between the armies of Emperor Francis II of the Holy Roman Empire Empire and Tsar Alexander I of Russia against their invading enemy, Napoleon Bonaparte.
In Uhlír’s fascinating account of one of the most famous battles of the Napoleonic campaign, excepting Waterloo of course, he points out that the battle took place on a different day for each of the three armies. For Francis II, the date was 2nd December 1805, for Alexander and the Russian army the date was 20th November and for Napoleon, Bonaparte it was 11th Frimaire year XIV. Francis and his army were using the Gregorian calendar introduced in 1582, although it was not universally adopted throughout Europe – indeed, England didn’t change until 1752. Alexander was still using the old Julian calendar – the Russians did not change to the Gregorian calendar until 1918. Napoleon was using the French Revolutionary Calendar, introduced in 1793, but back-dated to September 1792 to mark the beginning of the new republic and each successive year numbered from then on. It must have caused some confusion for the Austrians and the Russians when agreeing a date to face up to Napoleon and the French would have had to convert the traditional dates into their new scheme.