222 The Origins of the Thirty Years War and the Revolt in Bohemia, 1618
modern Karlsruhe to Bacharach, together with a smaller but more com-
pact section east of the Rhine and south of Mainz, including Friedrich’s
capital city of Heidelberg. Most of the lands west of the Rhine did not
actually belong to Friedrich, as they were sub-divisions of the Palatinate
owned by other branches of his family, but ironically these were among
the first areas occupied by the Spanish forces and made up three-quarters
of the territory in their hands by the end of 1620.^49
Archduke Albrecht had originally envisaged a campaign in which the
Union army would be confronted with his own advance from the west
and with the League army coming from the east, but the terms of the
treaty of Ulm precluded the latter, as did Maximilian’s need to hasten
towards Bohemia before time and money ran out completely. Concerns
about facing the Union alone thus added to Albrecht’s unease about
the necessary legal justification, but the preparations were already in
hand and had acquired a momentum of their own. Hence he set about
recruiting additional men, placing the invasion in the charge of Spain’s
leading general, Ambrosio Spinola, but it was well into August and
Tilly’s campaign in Upper Austria was virtually over before they began
to move.^50
The mustering place was Koblenz, in the lands of the elector of Trier,
where Spinola himself arrived on 18 August. A few days later he marched
his army east towards Frankfurt am Main and then to Mainz, where he
crossed the Rhine on 5 September, moving on south to enter Palatine
territory for the first time and to threaten the town of Oppenheim.
Ansbach moved to meet him, and on 8 September the two armies faced
each other in battle order, but no action followed. True to his Spanish
military training, Spinola preferred a war of attrition, and in any case
his objective was not to fight and defeat the Union army but to occupy
the Palatinate. Hence he slipped away, dividing his forces and sending
them to take one town after another, while Ansbach tried, largely in
vain, to follow or pre-empt them. In early October the latter received
reinforcements, a large troop of Dutch cavalry under Prince Frederick
Henry of Orange and over 2000 English volunteers under the command
of Horace de Vere, while Spinola, his attempt to intercept them having
failed, sent for reinforcements of his own from the Netherlands.^51
The campaign was by no means one-sided, although limited to skir-
mishes, and in some cases Union forces re-took places which had been
captured by the Spanish, but nevertheless Spinola steadily extended
his hold on the Palatinate west of the Rhine, garrisoning the towns
and extracting contributions from the population to finance his army.
He repeatedly evaded Union attempts to bring him to battle, tactics