All Chiasson families in Louisiana appear to be of Acadian stock. According to Bona Arsenault, the founder of the clan in America was Guyon Chiasson dit LaValée of La Rochelle, France, who arrived in Acadia ca. 1660, eventually settling in the Beaubassin district.* After the English drove the Acadians from their homeland (1755), several of Guyon's descendants fled to Louisiana; some came directly from Acadia, others via the Carolinas, still others by way of France. From these descend most of the Chiassons who live in the state today.

Two great-grandsons of founder Guyon-Pierre (m.

ca. 1755 Osite Landry) and Paul (m. ca. 1770 Marie-Madeleine Blanchard), both sons of Abraham and Marie Poirier of Beaubassin-were the first Chiassons to arrive in Louisiana.

By 1766 both were recorded as living along the Mississippi River in Cabanocé (St. James Parish); later Paul moved upriver to St. Gabriel in Iberville Parish.

Descendants of Pierre and Paul may have remained along the river for most of the nineteenth century,4 but few Chiassons live there today.

More important for the establishment of the Chiasson name in Louisiana was a probable brother of Pierre and Paul-Joseph Chiasson (m. ca. 1755 Annette Sonnier), whom the English held prisoner in Halifax for some time after the Expulsion.

That Joseph and his wife actually arrived in Louisiana is uncertain, but their son, Jean-Baptiste, was living in the Opelousas area in the early 1780s.

There, in 1786, he married Marie LeBlanc,7 and the two began a large line of the clan, particularly in the southern part of the Carencro prairies within the jurisdiction of Attakapas Post (St. Martinville). Church records suggest that a substantial part of the Chiasson families living in Lafayette and St. Martin parishes during the nineteenth century belonged to that family line.

Equally significant for the establishment of the Chiasson name in the Carencro area was an Acadian of that name exiled in France, who came to Louisiana in the migration of 1785-Basile Chiasson, with wife Monique Comeau and children.

Spanish authorities sent Basile and family to the Opelousas area, where he settled probably along Bayou Bourbeaux.

After the death of Monique he married (1789) Marie-Anne Thibodeaux, but only one of their sons, Louis (m. 1817 Marie Sonnier, 1828 Suzanne Dugat) managed to carry on the Chiasson name, chiefly in the Carencro area. Not until the 1890s did Chiasson families from St. Martin and Lafayette parishes begin to migrate into the southwestern part of the state.

Two other Acadian refugees from France were responsible for the establishment of the Chiasson name in the Lafourche-Terrebonne area, which today contains a third of Louisiana's households of that name. Jean Chiasson, wife Anne Soigne, and sons Joseph and Pierre arrived in the 1785 migration,13 son Pierre (m. 1805 Marguerite LeBoeuf) settling along Bayou Terrebonne as one of its early pioneers.

Probably all small farmers and swampers, his descendants made homes along the bayou near Montegut.

The second Chiasson refugee, also named Jean, apparently arrived in Louisiana with wife Marie-Josephe Dugas in the 1780s.

His son, Joseph-François (m. 1789 Marie Simoneaux, 1798 Marie-Marguerite Lejeune), settled along the Lafourche, as did most of their descendants, who resided between Thibodeauxville and Larose.

Three of Joseph's grandsons, Évariste-Aléxis (m. 1843 Marie-Adele Hymel), Pierre-Eugène (m. 1835 Josephe Usée), and Pierre-Georges (m.

1854 Doralise Hymel) all settled in the Chackbay area north of Thidodeauxville, where many of their descendants live today.

Two other grandsons, Sylvain-Théodule (m. 1847 Eugénie LeBlanc) and Paul-Adrien (m.

1850 Marie Pontiff, 1853 Pauline Richard, 1860 Estelle Thibodaux) and their descendants made homes along the Lafourche in the vicinity of Raceland, Lockport, and Larose