Baroque Flemish composer Carolus Hacquart was born around 1643 in northern, Spanish-administrated Bruges. Hacquart traveled south to Amsterdam in the early 1670s in search of work in a more lucrative atmosphere, and while his instrumental ability was well received, his "Popish" choice of religious affiliation was not, and his earliest publication, Cantiones sacrae (1674), utilizes altered Latin texts sufficient for protestant, and not liturgical, use. Also in 1674 Hacquart composed the music for De triomfeerende min, a pastoral commonly referred to as the first "opera" in the Dutch language, although the late scholar Pieter Andriessen disagrees, stating that this work was more the equivalent of a masque or "semi-opera." Poet and diplomat Constantijn Huygens took up Hacquart's cause, calling him "a grand master of music," and helped arrange for Hacquart's transfer to The Hague in 1679. In The Hague, Hacquart was engaged to play organ in a secret, surreptitious chapel where the city's Catholics were permitted to worship. After 1686 there is no mention of Hacquart in civic records in the Low Countries, and Andriessen suggested that Hacquart may have left for England with William III in 1689 as most of the unique sources for his work are found there. Hacquart was certainly dead by 1703, when his eldest son filed a will leaving his property to his "orphan sister." Outside of De triomfeerende min, Hacquart's reputation rests on three publications, the aforementioned Cantiones sacrae, a collection of very early trio sonatas entitled Harmonia parnassia (1686), and Chelys (1686), a set of 12 suites for bass viol. Although the single surviving copy of this early print does not contain a part book for the continuo, and it has become customary among performers to add a continuo of their own, it is entirely possible that these were intended as solo sonatas without continuo -- the only surviving portrait of Hacquart shows him playing a bass viol. The sonatas are more impressive than the vocal pieces, as they are harmonically exploratory and demonstrate an interesting variety of rhythmic ideas, in part drawn from the country dance music Hacquart would have known from his native Bruges. Although barely known outside of The Netherlands, Dutch scholars estimate that Hacquart was the most important Flemish musician in the latter half of the seventeenth century, and perhaps the last of the great Franco-Flemish composers whose lineage begins with Guillaume Dufay.