A sontag, also known as a bosom buddy, habit shirt, or heart hugger, is a triangular shawl that comes over the shoulders, across the body, and then ties in the back and front. The term sontag is reported to come from the German opera singer Henriette Sontag, most popular slightly before and during the Civil War era.
The pattern that inspired me was originally published in Godey’s Lady’s Book in January 1860. Godey’s was a popular magazine for women published in Philadelphia from 1830 to 1898. Many issues of this long-out-of-print periodical have been digitized and are available online (see Resources).