 The most likely explanation is that it was based on the traditional herding cry of German shepherds.. One theory is that it is an acronym from the Latin "Hierosolyma est perdita" ("Jerusalem is lost"), said (without verifiable evidence) to have been a rallying cry of the Crusaders.The "acronym theory" was attributed to a single letter published in a British newspaper on 28 August 1819, some weeks after the riots.Cornell's Michael Fontaine disputes this etymology, concluding that the "acrostic interpretation ... has no basis in fact.