Several of us who are members of South Tishomingo County Historical Society on Facebook have been researching the Battle of Vincent's Crossroads. If you are interested in the battle I suggest you consider joining that group and reading back through the posts about the battle.
To summarize what I believe about the battle: Vincent's Crossroads was the intersection of the Aberdeen-Fulton/Iuka Road and a road from Bay Springs, probably the Bay Springs/Russellville Road. The Aberdeen/Iuka Road, I believe, closely corresponds to Old Highway 25, and I think we have a good grasp of where it ran. The Bay Springs/Russellville Road is unknown. There is a theory that Red Bay, Alabama, on the Mississippi state line, was called Vincent's Crossroads in the mid-19th century, but I don't subscribe to that theory.
Based on a few artifacts found by other people and based on the knowledge of the location of the Widow Clark's house, which no longer exist, but the property is owned by her descendant, the battle seems to have begun around the Belmont city limits on the northeast side of the town. I believe Ferguson's Brigade, traveling from Cane Creek near Tuscumbia, Alabama, crossed Bear Creek near or south of the Dennis Bridge and north of the Ten Islands section of the creek. I believe they struck the Aberdeen/Iuka Road near Dennis, Mississippi, where they turned south. I think they encountered the first elements of the 1st Alabama somewhere at a crossroads and church called Possum Trot or between there and the town limits of Belmont.
I think Vincent's Crossroads corresponds to either the Possum Trot crossroads or a crossroads that was somewhere within the current Town of Belmont.