.. more tailored look in the mid-1860’s compared to even the early 1860’s. The difference can clearly be seen in the junction between bodice and skirt. On the later model, there isn’t one. We can see developing the next fashion eras with the cuirasse (armor-like) long bodice of the late 1870’s to come.
(Left: American example 1862 from the MET; right Harper’s Weekly again)