Because Bern and Zürich had been preparing the war for a long time, they seized the offensive. Bern opened the first war phase on 26 April, when its first troops crossed the river Aar at Stilli, to support Zürich with the occupation of Thurgau and the assault on the abbatial lands. In mid-May, about 3000 Zürichers, 2000 Bernese, 2000 Toggenburgers and 1800 Protestant Thurgauers marched into the Princely Lands and first hit upon the abbatial city of Wil, that fell on 22 May after a short siege. The allies then pushed forward to St. Gallen and occupied the Abbey of Saint Gall and the Vogtei Rheintal. The abbot fled to Neuravensburg, a lordship north of Lake Constance that the abbey had acquired in 1699. The five Catholic cantons did occupy Rapperswil, but initially left the abbot without any support. In concordance with contemporaneous laws of war, the abbey and its goods were put an under a military governance and the chattel and riches were abducted to Bern and Zürich.
Question: Which event happened first, Bern opening the first war phase or the occupation of Rapperswil?
Answer: Bern opened the first war