From War to Peace 21
against any Swiss expansion.71 Once King Louis XI of France had rejected any
offer of military assistance, however, the only realistic alternative was to approach
Duke Charles the Bold of Burgundy, who had already set his sights on an eastwards
expansion of his duchy. In May 1469 Sigismund accordingly signed the treaty of
St Omer with Charles, whereby he was to receive a payment of 50,000 fl and the
promise of military support in any Swiss attack in return for mortgaging most of
Outer Austria—the Sundgau and the county of Ferrette in Alsace, together with
the four Forest Towns, and the fortress of Breisach on the Upper Rhein—to
Burgundy.72 Emperor Frederick III was outraged at the affront to Habsburg
prestige; Bern was dismayed, for it now had a rich and powerful neighbour on its
own doorstep.73 Over the five years of the Burgundian mortgage the tectonic
plates of Swiss politics shifted decisively.74
The Swiss cantons and the French king were quick to forswear any assistance to
Burgundy, should they be threatened.75 The Swiss in particular saw the need to
cover their backs geopolitically, for in the autumn of 1472 they initiated talks
with Archduke Sigismund which were to lead to the Perpetual Accord two years
later.76 Above all, they forged a new alliance known as the Lower Union (Niedere
Vereinigung) in 1473 with four imperial cities of Alsace—Basel, Strasbourg,
Colmar, Sélestat—which was subsequently joined by the bishops of Basel and
Strasbourg, and indeed Archduke Sigismund himself, with the intention of
redeeming the mortgage through a payment of 76,000 fl.77
The terms of the Perpetual Accord, when it was finally sealed in June 1474,
are significant as much for what they do not state as for what they do.78 Freedom
of commerce, agreement on where judicial appeals should be heard, the return
of archives relating to places which had changed hands, and the outlawing of
encroachments on persons and property were uppermost. Nothing was said
about a military alliance; any mutual assistance was to be rendered on strict
cash terms. Nothing, too, was said about altering the territorial status quo,
except that neither side was to admit the other’s subjects into any dependent or
protective agreement, or Burgrecht. Tacitly, therefore, Swiss occupation of the
Thurgau was recognized.79 Only the provision that the four Forest Towns
should expressly swear to uphold the accord and remain militarily open to the
Swiss hinted at the troubles which had gone before. In short, it was an alliance
of convenience, not solidarity, evident from the fact that several Swiss cantons
71 Baum, Sigmund, 293–54. 72 The sum was actually paid. EA II, 398 (no. 634).
73 Stettler, Eidgenossenschaft, 229–30.
74 See now fundamentally Claudius Sieber-Lehmann, Spätmittelalterlicher Nationalismus. Die
Burgunderkriege am Oberrhein und in der Eidgenossenschaft (Veröffentlichungen des Max-Planck-Instituts
für Geschichte, 116) (Göttingen, 1995).
75 EA II, 413 (no. 658). 76 EA II, 435–7 (no. 692).
77 EA II, 441–2 (no. 699). On the Lower Union see Sieber-Lehmann, Spätmittelalterlicher
Nationalismus, 91 ff.
78 Negotiations in EA II, 473–82 (no. 735); text in EA II, 913–16: Appendix 51.
79 Giger, ‘Gerichtsherren’, 16.