I have always thought that this Annie by Foster bears a passing resemblance to another Annie, that of the Scottish Folk Song, Annie Laurie. It is an old Scottish song based on a poem said to have been written by William Douglas (1682?–1748) of Dumfries and Galloway, about his romance with Annie Laurie (1682—1764). The words were modified and the tune was added by Alicia Scott in 1834/5. What should be noted is that Annie Laurie was very popular song among Scottish and Irish soldiers before and during the American Civil War.
See what you think - I wonder if the opening interval of Gentle Annie was a subconscious reference to the Scottish Song that arrived during the Civil War?
Gentle Annie by Foster was published in 1856
D'Ammassa Spruce/Spruce Double Top