http://en.wikipedia.org/wiki/Les_AspinCriticism and final days in office
In September General Powell asked Aspin to approve the request of the U.S. commander in Somalia for tanks, armored vehicles and AC-130 Spectre gunships for his forces. Aspin turned down the request. Shortly thereafter Aideed's forces in Mogadishu killed 18 U.S. soldiers and wounded more than 75 in attacks that also resulted in the shooting down of three U.S. helicopters and the capture of one pilot. In the face of severe congressional criticism, Aspin admitted that in view of what had happened he had made a mistake, but stated that the request for armored equipment had been made within the context of delivering humanitarian aid to Somalia rather than protecting troops. In an appearance before a congressional committee to answer questions about the Somalia disaster, Aspin made an unfavorable impression and appeared weak in response to the detailed probing and criticism of his performance. The president publicly defended Aspin but made clear that the White House was not involved in the decision not to send armor reinforcements to Somalia. Several members of Congress called on Clinton to ask for Aspin's resignation.
On 15 December 1993 President Clinton announced Aspin's resignation, for personal reasons. Given the problems that Aspin encountered during his short term, most obviously the losses in Mogadishu, observers assumed that the president had asked him to step down. Speculation in the media centered on the Somalia embarrassment and on Aspin's differences with the Office of Management and Budget over how much the Defense budget should be cut. The secretary's health problems, of course, may well have also been a factor. One news magazine stated that Aspin's major handicap was "neither his famously unmilitary bearing nor his inability to discipline himself or the enormous Pentagon bureaucracy; it is his politician's instinct for the middle ground on defense issues." Aspin continued to serve as secretary of defense until February 3, 1994, when William J. Perry took office.