GEOLOGY OF THE WAR OF 1812: TERRAIN INFLUENCES ON THE BATTLE OF THE COTE SANS DESSEIN, MISSOURI TERRITORY

The connections drawn between geology and historical events provide opportunities for place-based curriculum development and geosciences education. Students learn that geology has influenced their communities. The War of 1812 provides a compelling backdrop for understanding the influence of geology on battlefields in Missouri. Cote Sans Dessein, where French-American settlers fought Sac and Fox warriors loyal to the British, demonstrates how geological influences are critical to outcomes of engagements.

The Battle of Cote Sans Dessein took place along the Missouri River in present-day Calloway County. Cote Sans Dessein translates as "hill without design". It is an elongate, erosional remnant of lower Ordovician Jefferson City Dolomite (Ibexian Series) in the middle of the Missouri River floodplain, approximately 20 km east of Jefferson City. The ENE-WSW linear ridge is 1.7 km long, 200 m wide at its base, and stands 45 m in relief. The settlement adjacent to Cote Sans Dessein was established in 1808 as a trading post at the northeastern extent of Osage lands, near the confluence of the Missouri and Osage rivers. By 1815, about 20 families lived in the village. A few cabins, barns, and two blockhouses, known as Roy¹s and Thibault¹s forts, were constructed on the east end of the ridge, 200 to 300 m apart. A log magazine was located between them.

On April 4, 1815, a party of Rock River Sac and Fox, numbering about 200, were spotted west of Cote Sans Dessein. The settlers, led by Capt.

Coursault, engaged the Sac and Fox in the woods below the hill and north of the village in a running battle that raged most of that afternoon.

Meanwhile, a group of Native Americans laid siege to the blockhouses. High ground, defensive structures, and adept reloading of two rifles by women in Roy¹s fort allowed Louis Roy to ward off attempts to overrun it. Resorting to fire arrows and torches, the roof was set afire, but the heroic actions of Madame Roy kept it from burning completely. In all, several barns were destroyed, and before leaving the village, the magazine was set ablaze and exploded, punctuating the end of the battle. None of the historic structures remains; a quarry on the east end of the hill has removed one historic site.

With development of the Missouri River for barge traffic, the course of the Osage has was diverted downstream, east of Cote Sans Dessein.