Jacob Kettler was a notable figure in the 17th century, known for his role as the Duke of Courland and Semigallia. He ruled from 1638 until his death in 1682 and is recognized for his efforts to develop the economy and trade in his duchy. Kettler sought to establish Courland as a maritime power, promoting shipbuilding and overseas trade. Kettler was also involved in various diplomatic efforts, including alliances with other European powers. His reign is marked by attempts to modernize his territory and improve the welfare of his subjects. Despite facing challenges, he left a lasting impact on the region's history.