The alliance of the four forest cantons of Uri, Schwyz, Unterwalden and Lucerne with the city of Zürich in 1351 set much in motion. The town of Zug was seen as having Habsburg ties with the cities of Zürich and Lucerne, and therefore had to be conquered. It is likely that this was more for political than economic reasons: the Lucerne market was very important for central Switzerland, but also strongly dependent on the city of Zürich. Zürich initiated a siege on Zug with the federal army in June 1352. Zug surrendered. On 27 June 1352 Zürich, Luzern, Zug, Uri, Schwyz and Unterwalden formed an alliance. Zürich's saw this ‘Zugerbund’ (Zug alliance) as an alliance of convenience. For the town of Zug, little changed, and Zug remained Habsburg. That same year, the Zug alliance was declared invalid by all parties. A period of Schwyz domination then followed. Only gradually did Zug become sovereign and federal.