Henry II the Pious
The town's name comes from Polish "olsza" ("Alder"); "Olcha" is an Old Slavic word for this common plant and tree. On 22 February 1255 the Silesian duke Henry III the White, son of the Polish High Duke Henry II the Pious, vested "civitas nostra Olsnicz" ("our town Oleśnica") with town privileges.