Immediately on his return from England in 1637, Rupert joined his brother Maurice in the army of the Stadtholder. Prince Henry was just then engaged in the siege of Breda, a town which was oftener lost and won than any other in the long wars of the Low Countries. Many Englishmen were fighting there, in the Dutch army: Astley, Goring, the Lords Northampton and Grandison, with whom the Palatines were already well acquainted, besides others whom they were to meet hereafter in the English war, either as friends or foes. The two young princes acted with their usual energy and "let not one day pass in that siege, without doing some action at which the whole army was surprised."[1] Once, by their courage and ready wit, they saved the camp from an unexpected attack. Waking in the night, Rupert fancied that he heard unusual sounds within the city walls. He roused Maurice, and the two crept up so close to the Spanish lines that they could actually hear what the soldiers said on the other side. Thus they discovered that the enemy was preparing to fall upon them at mid-night, and, hastening back to the Stadtholder, they were able to give him timely warning. Consequently, when the besieged sallied out, the besiegers were ready for them, and forced them to retire with great loss.[2] On another occasion Rupert's love of adventure led him into flat insubordination. Monk, afterwards Duke of {35} Albemarle, was about to make an attack upon the enemy's words, which was considered so dangerous that the Stadtholder expressly forbade Rupert to take part in it. But Rupert no sooner heard the Stadtholder give the order to advance, than he dashed away, anticipating the aide-de-camp, himself delivered the order to Monk, and, slipping into his company as a volunteer, took his share in the exploit. The Prince came off unhurt, but many of his comrades fell, and both Goring and Wilmot were severely wounded. The fight over, Rupert and some other officers threw themselves down on a hillock to rest; they had been there some time, when, to their surprise, a Burgundian, whom they had taken for dead, suddenly started up, crying: "Messieurs, est-il point de quartier?" The English officers burst out laughing, and immediately dubbed him "Jack Falstaff", which name he bore to his dying day.[3] What the Stadtholder thought of Rupert's mutinous conduct is not recorded. Eventually Breda fell to the Dutch arms, and Maurice was, immediately after, sent to school in Paris, with his younger brothers, Edward and Philip. He must have gone sorely against his will, especially as Charles and Rupert were proceeding to levy forces for their own attempt on the Palatinate. But Elizabeth was inexorable. She was resolved not to blush for the manners of her younger sons, as she declared she did for those of Rupert; and she was, besides, anxious to have Maurice in safety, seeing that the two elder boys were about to risk their lives in so rash a venture.