The Revolt Defeated 205sieges in the war between the Spanish and the Dutch in the Netherlands
had shown that relatively small garrisons could hold off substantial
armies almost indefinitely. Even without city walls and major earth-
works an army could build a fortified camp in a matter of days, and with
a good site on elevated ground this could be defended against much
larger numbers for a prolonged period. There are many examples from
later in the Thirty Years War.^4 It was rarely practicable for the besiegers
to seal off the perimeter of a city or camp entirely, as this could be as
much as ten miles long for a large army encampment, so that some
supplies got through, and sometimes reinforcements as well. This made
starving out the defenders a lengthy affair during which those outside
had their own supply and logistical problems to contend with. Moreover
the besieging army was just as effectively pinned down as the besieged
one while the campaigning season slipped fruitlessly by, which was pre-
cisely what Maximilian could not afford if he were to deal with Bohemia
before the winter.
There were other dangers for him too. The greatest fear of besieging
forces was an attack from the rear by a relieving army, so that they
might find themselves caught between the newcomers on the one side
and the defenders sallying from their camp on the other. If their army
were trapped at Ulm the Protestant Union could conceivably gather
additional forces by the early autumn, particularly if their previously
reluctant English and Dutch allies were moved by the changed situation
to contribute troops. Then there was the elector of Saxony, who had
with difficulty been recruited to the coalition to attack Bohemia and
was under Protestant pressure as a result. He had been signed up to help
crush the revolt, not to become involved in a war against the Protestant
Union. The elector, and the other substantial north German princes who
had not been persuaded to go beyond neutrality towards the Bohemian
campaign, might not be prepared to stand idly by while the Union were
defeated, their previous differences with its leadership notwithstanding.
Should a wider conflict develop in Germany, Maximilian would have no
resources available to pursue his original objective, and indeed Bethlen
Gabor and the Ottoman sultan might thus be encouraged to give further
assistance to the Bohemians.
The duke was in a dilemma. He could not move away towards
Bohemia leaving the Union army at large behind him, as he informed
Ferdinand sharply, because of the risk to which this would expose to his
own Bavarian homeland, but he could not attack it for fear of provoking
a wider conflict which would make it impossible for his army to leave
Germany.^5 Nor was he yet sure of Spanish support, as Archduke Albrecht