it seems that there was a personal conflict between Clark and Shelton, and some disagreements over policies in Bosnia. This link contains some early information; since then, Clark has spoken out somewhat on this issue, explaining this quite well to Tweety on Harball last Monday night.
An exerpt from the article on the link:
http://www.epivox.com/wesleyclark-knoxville/glowing_reports_NYT.cfmThe comments of his commander when he oversaw a tank battalion in
Germany in 1977 were typical: "The most brilliant and gifted officer
I've known." The commander, Col. Charles G. Prather IV, added: "I
have never been more impressed with an officer's talent and
dedication." He added that he should rank with men like Douglas
MacArthur.
A year later, the future General Clark, now 58, had advanced to
assistant executive officer to Gen. Alexander M. Haig Jr., then
Supreme Allied Commander of NATO. In his evaluation, General Haig
wrote: "Major Clark is an officer of impeccable character with a rare
blend of personal qualities and professional attributes which
uniquely qualify him as a soldier-scholar."
The documents, given by the campaign to The New York Times, are
performance evaluations that begin with General Clark's admission to
West Point in 1962 and cover more than 30 years of his military
career, in which he earned such decorations as a Silver Star, a
Bronze Star and a Purple Heart.
The records include high praise from Colin L. Powell, now secretary
of state and then an assistant division commander at Fort Carson,
Colo., who called then-Lieutenant Clark an officer of "the rarest
potential." The evaluations end in 1993, when General Clark earned
his second star; officers at or above the rank of two-star general do
not receive such performance reviews.
Another link with some comments about this issue:
http://pub73.ezboard.com/fwesleyclark200463811frm12.showMessage?topicID=36.topicThis link has comments from then-secretary of defense William Cohen, who states that there were NO job performance issues, and that many positions were being replaced at that time; I had read somewhere not too long ago (can't remember where, will search, sorry!) that the guy that replaced Clark was a buddy of Cohen's who had no other position to be promoted to so he got the NATO thing.
http://www.southernfriedmind.com/cgi-bin/mt-comments.cgi?entry_id=146Hope that helps!