To run away or abscond. A comic American word from ab and squat, to go away from your squatting. A squatting is a tenement taken in some unclaimed part, without purchase or permission.--Ebenezer Brewer's Dictionary of Phrase and Fable, 1898
[August 10:] Feast Day of St. Besse,
a third-century Roman soldier who later became a patron of draft dodgers. He "took French leave" of military service near Lake Geneva in Switzerland, sneaking off to preach to residents of the Soana Valley. Besse's successful absquatulation helped establish the long-standing Swiss policy of neutrality, although he was eventually killed by unimpressed alpine pagans. J. B. Lippincott's Everyday Phrases Explained (1913) offered some background regarding the sniping expression French leave, which reflected earlier Anglo-Franco relations: "To take French leave is to go off secretly, without formal notice or farewell. The French have a corresponding phrase [s'en aller à l'anglaise], to depart like the English. Both expressions date from the time [the 1770s] when an entente cordiale was never dreamed of, and each country had a very poor opinion of the other's manners."
-M. le Gneech