- see also Alexander Horn (disambiguation)
Horn was born in Oyne, Aberdeenshire. In 1772 he was admitted to the Catholic seminary in Regensburg, perpetual seat of the Imperial Diet of the Holy Roman Empire. He took the religious name Maurus and was ordained around 1785. By 1790 he was an esteemed librarian at the Scots Monastery while at the same time working as the Regensburg agent for the British ambassador in Munich. He cultivated close ties with the Thurn and Taxis family and other influential people in the region. Despite being a monk, his social life led to him being described as a "wild young fellow".
Horn wrote anonymously condeming France's activities in undermining the Holy Roman Empire. He supplied the material that formed the core of John Robison's 1797 allegation of an international conspiracy of freemasons, illuminati, and Jacobins. In 1799 he travelled to England, meeting with members of William Pitt's government including Earl Spencer. He subsequently used his bibliographical expertise to acquire rare books and manuscripts for Spencer's library.
When in 1802 the Eternal Diet of Regensburg under pressure from Napoleon Bonaparte, determined to secularize all the church lands of the Empire, the Scots Monastery was uniquely successful in avoiding this fate. Horn and his abbot, Charles Arbuthnot lobbied Macdonald and Lauriston, Scottish Catholic generals in the French army. He was by now the official British agent in Regensburg and further appealed to the British government. The Scots Monastery was exempt from German church authorities coming under the sole authority of Holy See and the two priests successfully obtained the support of the cardinal protector of Scotland in Rome. An express exemption was made in favour of the Scots abbey although it was not allowed to take any new novices.
- Mark Dilworth, ‘Horn, Alexander (1762–1820)’, Oxford Dictionary of National Biography, Oxford University Press, 2004