Upvote:5
Yes indeed. As early as 1346, corpses with symptoms of the Black Death seem to have been catapulted by the Mongols into the city of Caffa, Crimea during a siege.
Reference: Wheelis M., Biological warfare at the 1346 siege of Caffa. Emerg Infect Dis, Sep 2002. Available here
It may be noted that this use was not very effective, since knowledge of the precise nature and transmission mechanism of the disease was not available until the 1890s. So, this is perhaps more an opportunistic use of sick individuals in a war scenario than a truly weaponised disease.