"Rev. Pierre De Smet (1801-1873) was born in Belgium but came to America in 1821, joined the Jesuit Society and begun his work with the Indians. In his work he established 16 treaties, crossed the ocean 19 times and travelled 180,000 miles on his errends of charity for the Indians who knew him as 'The Sincerest Friend.'
"On July 5, 1840, in the presence of 2000 Indians, trappers, and traders he offered the first Mass in what is now Wyoming on an alter of native stone decorated with wild flowers. In Father De Smet's own words, 'It was a spectacle truly moving to the heart of a missionary that this immense family, composed of so many tribes should prostrate themselves in equal humility before the Divine Host.'
"The monument at the site was erected in 1925 and a commemorative mass is offered there annually in July. On July 4, 1940, the 100th anniversary of the first mass, a Pontifical High Mass was offered by the Most Rev. Bishop McGovern assisted by more than 30 priest and attended by about 2000 people."