Any particular accomplishment/s, or just not given sufficient credit for what he did overall?
What I know of his career on the whole is cursory at best, mostly the Wagon Train of Wounded post-Gettysburg.
Considering his lack of military training and his being underrated by the West Pointers and Lee to some point almost akin to Jackson and Ashby. He performed very well. I find Imboden to be very intrigueing, he goes from being a captain in an artillery unit to basically being the head honcho in the mountains where Lee failed to succeed. He convinces Lee to send him some infantry to help on the Imboden-Jones raid, though I think if not for Jones being involved Lee would not have sent the 25th and 31st va to him because of his own underrating of him as a General. But back to his mountain (Guerilla type affairs) he was dealing with what I would compare to a vietnam, iraq, type scenario, wasn't typical warfare, more like the family feud, bottom landers vs upper landers, coal miners vs salt peter miners...Granted it wasn't a huge scale of forces he was commanding but it definately took a different type of man to fight in those areas and he performed very well. When I first started looking into my ancestors, I knew about Gettysburg and all the other great battles and big name Generals but I didn't know some of the minor role players that played huge roles till after I got involved in geneology. The fact that Imboden with a small force of cavalry (more to mounted infantry) was able to use wagon drivers and his small force to save the Confederate Army and Lee during the retreat from Gettysburg gives great credit to his ability as a military leader and doesn't seem to get as much credit as say Chamberlain at round top, Greene at Culps hill...
Lee says of one of Imboden's regiment's, which I think was the 18th Va Cavalry, under Imboden's brother, (which my GGGrandfather, and 3 of my GGgrand Uncles fought with)..."They are unsteady, and, I fear, inneficient" Yet, these would be the men that save his army, and his 4,000 wagons.
2100 dismounted cav, 700 wagoneers, and 24 cannon, Imboden chose to stand and fight at Williamsport and repelled Buford's division of about 7,000 cavalry. He armed and put about 350 of these wagon drivers on his flanks put his main force in the center and drove back a veteran cavalry force. The same force mind you that gets such great laurels for their delaying actions at Gettysburg.
"As we could not retreat further, it was at once made known to the troops, that unless we should repel the threatened attack we should all become prisoners, and that the loss of his whole transportation would probably ruin General Lee" General John D. Imboden.
So, I would say that Imboden was underrated as a General, even at the point that Lee has to put his trust in him to guard his wagon train, he makes a comment about one of the regiments being lacking, therefore underrating them which underates their commanding officer. Imboden would rectify this by performing as good as any other applauded general of the war.