The phrase "unconditional surrender" means surrendering completely without any conditions or terms. It implies giving up entirely without negotiating or asking for anything in return. Full definition
The Museum of Unconditional Surrender consists of a group exhibition, lectures, a museum night and publication, in which the experience of the exhibited objects to the audience is put to the test. (galeriepoggi.com)
Yet the scale of the air war has gone far beyond the UN authorization, as did the continuing escalation of the war aims so that by February 15 Pentagon projections were assuming the demand for unconditional surrender rather than withdrawal, and by February 25 flanking actions were undertaken to prevent withdrawal. (religion-online.org)