The Allies offered peace terms in the Frankfurt proposals in November 1813. Napoleon would remain as Emperor of France, but it would be reduced to its "natural frontiers." That meant that France could retain control of Belgium, Savoy and the Rhineland (the west bank of the Rhine River), while giving up control of all the rest, including all of Spain and the Netherlands, and most of Italy and Germany. Metternich told Napoleon these were the best terms the Allies were likely to offer; after further victories, the terms would be harsher and harsher. Metternich's motivation was to maintain France as a balance against Russian threats, while ending the highly destabilizing series of wars.
The Frankfurt proposals sought to reduce France to what?
its "natural frontiers."