Once More unto the Breach 149account the possibility that strong reinforcements might be on the way
to Tilly. Hence he decided, not for the first time, to ignore the conven-
tional military wisdom of the age, and to force a crossing of the river
in the face of Tilly’s defences. It was a risky venture, as Horn, second-
in-command of the army, pointed out.^11
On the morning of 13 April 1632 Gustavus drew up his army in bat-
tle order along the river opposite Tilly’s positions, as though about to
make an assault, but this was merely a diversion while his engineers
constructed emplacements for three powerful artillery batteries. This
work continued into the night, during which bridging materials were
also brought up. On the following day an artillery battle across the river
ensued, in which the Swedes were better placed because of the much
larger number and heavier calibre of their guns. Nevertheless this too
was essentially a diversion while preparations for bridging the river
continued a little further to the south, unobserved by the Bavarian
commanders. Early on 15 April elite Finnish troops crossed by boat to
a small island in the middle of the river, a bridge to which was quickly
constructed, and a strong force followed. Tilly noted the activity and
moved up reserves to counter it, but the Finns crossed the second part
of the river in their boats under cover of a massive smokescreen and
an artillery bombardment, with the bridge being rapidly extended to
follow them. Heavy fighting followed into the afternoon, during which
the Swedes could make little progress from their bridgehead but the
Bavarians were unable to dislodge them.
Meanwhile Gustavus sent cavalry units in both directions along
the river to try to find places to ford or swim across. Both were suc-
cessful, but the smaller body to the north was quickly pinned down
by the defenders. To the south a substantial force crossed late in the
afternoon, but it was immediately attacked by Tilly’s cavalry reserve,
and a similar situation to that at the bridgehead developed, where they
neither made ground nor were repulsed. As evening approached both
Tilly and Aldringer, who was commanding a body of Imperialist troops
attached to the army, were wounded and put out of action, leaving the
non-soldier Maximilian in command. At this stage the Bavarians were
by no means defeated, but as darkness fell it was obvious to Maximilian
and his colonels that they could not prevent Swedish forces crossing
in strength at their bridgeheads during the night. Rather than face a
renewed onslaught from the much larger army on the following day
they quietly evacuated their men and made for Ingolstadt, an operation
conducted so skilfully that the Swedes discovered it too late to mount
an effective pursuit.^12