Saffron demand skyrocketed when the Black Death of 1347–1350 struck Europe. It was coveted by plague victims for medicinal purposes, and yet many of the farmers capable of growing it had died off. Large quantities of non-European saffron were therefore imported. The finest saffron threads from Muslim lands were unavailable to Europeans because of hostilities stoked by the Crusades, so Rhodes and other places were key suppliers to central and northern Europe. Saffron was one of the contested points of hostility that flared between the declining landed gentry and upstart and increasingly wealthy merchants. The fourteen-week-long "Saffron War" was ignited when one shipment of saffron was hijacked and stolen by nobles. The load, which was en route to the town of Basel, would at today's market prices be valued at more than 500,000. That shipment "was" eventually returned, but the wider 13th–century trade was subject to mass piracy. Thieves plying Mediterranean waters would often ignore gold stores and instead steal Venetian- and Genoan-marketed saffron bound for Europe. Wary of such unpleasantness, Basel planted its own corms. Several years of large and lucrative saffron harvests made Basel extremely prosperous compared to other European towns. Citizens sought to protect their status by outlawing the transport of corms out of the town; guards were posted to prevent thieves from picking flowers or digging up corms. Yet ten years later the saffron harvest had waned. Basel abandoned the crop.