Willem Bartsius (also spelt Bartius, Baldeus and Baldesius), Dutch painter. His father, Paulus Pietersz. Bartsius, was a stadpensionaris, or legal adviser to the town council of Enkhuizen and his sister, Aagje married the landscape and figure painter Pieter Simonsz. Potter and gave birth to the famous animal painter Paulus Potter. Little is known of the artistic formation of Willem Bartsius or of his movements in the 1620s and 1630s. He might have accompanied his brother-in-law Pieter Potter to Leiden in 1628. During the early 1630s it is also possible that he may have moved for a time to Haarlem. The first clear record of his activity is in 1633 when he registered as a member of the Alkmaar Guild of St Luke, becoming a Master in 1634. Bartsius's registration in the guild was prompted by a prestigious commission from the city of Alkmaar for a large group portrait of their militia company, the Officers and Standard Bearers of the Oude Schutterij of Alkmaar (1634, Alkmaar, Stedilijk Museum), a flamboyant and reasonably accomplished composition somewhat in the manner of Hals. From the provincial city of Alkmaar Bartsius moved to Amsterdam around 1636, lured probably by the temptation of better financical prospects and the fact that his family had already settled there. He may have abandoned painting shortly afterwards as a result of the stiffness of the competition in the capital city. Bartsius's last signed painting is dated 1638 and there is no record of him after 1639 apart from a drawing of questionable authorship, signed and dated 1657. It is likely that he died in the late 1630s. Although described in the older art-historical literature as a genre and portrait painter, Bartsius's surviving output consists principally of history paintings, mainly biblical subjects, for which there was a ready market in and around Amsterdam at the time. He also painted allegories as well as themes from mythology, literature and portraits. //