By this time, Harrington's father had died, and his inheritance helped pay his way through several years of continental travel. There is some suggestion that he enlisted in a Dutch militia regiment (apparently seeing no service), before touring the Netherlands, Denmark, Germany, France, Switzerland and Italy. He was in Geneva with James Zouche in the summer of 1635 and subsequently travelled to Rome. In the light of this, Toland's reference to his visiting the Vatican, where he "refused to kiss the Pope's foot", probably refers to early 1636; meanwhile his visit to Venice helped bolster his knowledge of, and enthusiasm for, the Italian republics. The following decade, including his comings and goings during the Civil Wars, are largely unaccounted for by anything other than unsubstantiated stories, for example that he accompanied Charles I to Scotland in 1639 in connection with the first Bishops' War. In 1641–42 and in 1645 he provided financial assistance to Parliament, providing loans and perhaps also collecting money on behalf of Parliament in Lincolnshire. Yet, around the same time, he was acting as 'agent' for Charles Louis, the Prince Elector Palatine, who was nephew of Charles I and whose brother Prince Rupert led the Royalist forces in the English Civil War. Charles Louis and his mother had declared their support for Parliament in 1642.