148 Wallenstein
Perversely it was Maximilian and Tilly who opened hostilities in
southern Germany in 1632. Gustavus had left one of his generals, Gustav
Horn, to hold captured territories in Franconia around Würzburg, and
over the winter Horn had also occupied the neighbouring bishopric of
Bamberg. Although well away from Bavaria itself this was close to the
Upper Palatinate, which Maximilian had acquired from the dispossessed
Frederick, and this in turn bordered on the western edge of Bohemia.
Despite the weakened state of Tilly’s army Maximilian decided to go
on to the offensive, aiming to secure not only Bamberg but the link
to Bohemia, where he hoped to receive support from Wallenstein,
although he had not obtained his prior agreement.^10 Surprisingly, Tilly
succeeded in driving Horn out of Bamberg during March, thereby mak-
ing a small dent in the Swedish record of success, but it was one which
Gustavus would not allow to go unrepaired. By attacking the Swedes
Maximilian had abandoned his neutrality, thus freeing Gustavus from
the limited constraints of his Bärwalde treaty with France. The king
immediately changed his original plan for 1632, which had been to
move southwards from Mainz, through Swabia to the Danube, and then
east along the river towards Austria. Instead he marched back towards
Bamberg, joining up with Horn at nearby Schweinfurt. Tilly did not
wait for him, hastily abandoning his conquest and retreating to the
Bavarian fortress city of Ingolstadt, which he reached at the beginning
of April. Gustavus followed at a more leisurely pace, pausing to make
a triumphal entry into Nuremberg on the way, but he now clearly had
Bavaria in his sights.
Gustavus decided to cross the Danube upstream at Donauwörth and
to approach Bavaria from the west, from which direction the border
was defined and protected by the smaller but still substantial River
Lech. The Bavarians had destroyed the few bridges, so the nearest
feasible crossing point was a little south of the town of Rain, 25 miles
west of Ingolstadt, and here Tilly, accompanied by Maximilian himself,
quickly established a strong defensive position. His intention was to
delay Gustavus by forcing him to march further south looking for an
alternative crossing, difficult because of the seasonally high level of
the river, fed by melting Alpine snows. Twenty miles in that direction
would bring him to the important free city of Augsburg, Protestant
in sympathy but garrisoned and under Catholic control, so that the
Swedes would be further delayed by the need to capture it. Gustavus,
on the other hand, was well aware that Wallenstein was rebuilding the
Imperial army, although he did not know how far he had progressed
or when he would be ready to take the field, but he had to take into