Oxenstierna remarked that Fleetwood was a good man and that he would have had less trouble with Spens' old regiment if it had gone to Fleetwood rather than the Earl of Crawford, and in April 1631 he recommended Fleetwood to Gustav II Adolf with regard to recruitment. He was knighted by king Gustav II Adolf in Germany on 3 June 1632, and he was present at the battle of Lützen in November at which the king was killed. It is said that after the fall of Gustav II Adolf he held back retreating Swedish troops together with the King's court and army-chaplain, superintendent Dr. Jacob Fabritius.