17, 1466 through an alliance with Bern (and Solothurn). In Rapperswil, a Habsburg enclave on Lake Zürich within confederate territory, a pro-confederate coup d'état in 1458 led to the city becoming a protectorate of the confederacy in 1464. Duke Sigismund of Austria got involved in a power struggle with Pope Pius II over the nomination of a bishop in Tyrol in 1460. When the duke was banned by the pope, a situation similar to that of 1415 arose. The confederates took advantage of the problems of the Habsburgs and conquered the Habsburg Thurgau and the region of Sargans in the autumn of 1460, which became both commonly administered property. In a peace treaty from June 1, 1461, the duke had no choice but to accept the new situation. The Swiss also had an interest in extending their influence south of the Alps to secure the trade route across the St. Gotthard Pass to Milan. Beginning in 1331, they initially exerted their influence through peaceful trade agreements, but in the 15th century, their involvement turned military. 1403 the upper Leventina, as the valley south of the pass is called, became a protectorate of Uri. Throughout the 15th century, a changeful struggle between the Swiss and the Duchy of Milan ensued. In 1439, Uri assumed full control of the upper Leventina; the Duchy of Milan gave up its claims there two years later, and so did the chapter of Milan in 1477. Twice the Swiss conquered roughly the whole territory of the modern canton of Ticino and also the Ossola valley. Twice, the Milanese reconquered all these territories except the Leventina. Both times, the Swiss managed, despite their defeats, to negotiate peace treaties that were actually favorable for them. Burgundy Wars The Burgundian Wars were an involvement of confederate forces in the conflict between the Valois Dynasty and the Habsburgs. The aggressive expansionism of the Duke of Burgundy, Charles the Bold, brought him in conflict with both the French king Louis XI and emperor Frederick III of the House of Habsburg. His embargo politics against the cities of Basel, Strasbourg and Mulhouse prompted these to turn to Bern for help. The conflicts culminated in 1474, after duke Sigismund of Austria had concluded a peace agreement with the confederates in Constance (later called the Ewige Richtung). The confederates, united with the Alsatian cities and Sigismund in an "anti-burgundian league", conquered part of the