The fifteenth century saw continued expansion by the Confederation. Forces from Uri and Obwalden crossed the Gotthard to seize the Valle Leventina south to Bellinzona, in order to secure their trade route (crushing the armies of the Dukes of Milan as they did so), while Confederate forces took advantage both of popular uprisings against the abbot of St Gallen to extend their influence further eastwards, and of a dispute between Austria and Luxembourg to seize control of the fertile northern lands of Aargau.

After 1460, Swiss mercenaries became known and feared throughout Europe for their bravery and military skill, tested on battlefields in the west of the country fighting Charles the Bold of Burgundy. Celebrated victories at Grandson, Murten and Nancy in the years 1476–77 effectively wiped Burgundy from the map as a regional power, but nonetheless led to the first of many subsequent disputes within the Confederation over the balance of power between towns and countryside. Rural cantons were loath to see Bern – principal victor against Charles – become any more powerful, and only accepted the entry of Fribourg and Solothurn to the Confederation in 1481 on the condition that they took a role of arbitration between the cities and the countryside to moderate urban expansionism. Following Zürich’s victory in the Swabian War of 1499 – which won final and complete freedom for the cantons from the German Empire – both Basel and Schaffhausen joined the Confederation (1501), followed by tiny Appenzell in 1513. By then, the thirteen cantons possessed extensive subject territories, including Aargau, Thurgau and a swathe of Ticino. The first Swiss parliament, the Diet, met regularly in Baden as a forum to bring Confederate opinion together, both by discussion and – even at this early date – by majority voting.