He had now but 3500 men with him, 2700 having died from pestilence, famine, and disease.

He assisted General Banner in blockading the Imperialist garrison of Magdeburg, and his losses by fever and pestilence thinned his troops down to two small regiments; these were incorporated with the force of the Duke of Saxe-Weimar, and the Marquis of Hamilton joined the staff of Gustavus as a simple volunteer.
The king now determined to conquer the Palatinate, which was held by a Spanish army.

He drove them before him until he reached the Rhine, where they endeavoured to defend the passage by burning every vessel and boat they could find, and for a time the advance of the Swedes was checked.
It was now the end of November, the snow lay thick over the whole country, and the troops, without tents or covering, were bivouacked along the side of the river, two miles below Oppenheim.

The opposite bank was covered with bushes to the water's edge, and on an eminence a short distance back could be seen the tents of the Spaniards.
"If it were summer we might swim across," Nigel Graheme said to Malcolm; "the river is broad, but a good swimmer could cross it easily enough." "Yes," Malcolm agreed, "there would be no difficulty in swimming if unencumbered with arms and armour, but there would be no advantage in getting across without these; if we could but get hold of a boat or two, we would soon wake yonder Spaniards up." The next morning Malcolm wandered along the bank closely examining the bushes as he went, to see if any boats might be concealed among them, for the fishermen and boatmen would naturally try to save their craft when they heard that the Imperialists were destroying them.

He walked three miles up the river without success.