Brown created the model for his eagle in 1867 for his monument to Abraham Lincoln, the first erected in the United States, and placed in Prospect Park, Brooklyn, New York, in 1869. Brown had exhibited a bronze eagle at the National Academy of Design Exhibition in 1868, the premiere national exhibition venue for American artists at the time. The Gilcrease eagle, purchased by Thomas Gilcrease from a New York dealer in 1944, was likely cast in 1867-68 for that exhibition as no other casts are known aside from those made for the base of the monument.

From the exhibition:Frontier to Foundry: the Making of Small Bronze Sculpture in the Gilcrease Collection, December 2014 - March 2015.
Ann Boulton Young, Associate Conservator for the Gilcrease Museum, 2014.