The action by which James Butler had kindled so much indignation in the breast of the usually placid Gustavus is now unknown; but it must have been something very remarkable to excite such angry bitterness. Had Walter Butler been a Protestant, the king would, no doubt, have endeavoured to lure him into the Swedish service; but the wounded Imperialist was as famous for his strict adherence to the duties of the Roman Catholic church as for his gallantry in the field.
While lying thus helplessly at Frankfort, he was deeply stung and mortified by the rumour so wickedly and so industriously spread by the Imperial generals, that he had occasioned the loss of the town; and he cast his honour under the protection of the generous Gustavus.
"Sir," said the latter, "it is in my power to do your character ample justice, and in such a manner that it can never be controverted. I will bear full testimony to your faith and valour under my own hand and royal seal."
Assuming a pen, he drew up a certificate, which set forth the heroism displayed by Butler in the strongest terms, and added, "that if the Imperial generals, instead of acting like poltroons, had performed but a fifth part of what this gallant Irishman had done, he (Gustavus) should never have been master of Frankfort, but after an obstinate siege alone."
"This, sir," said the king, "is no more than is due to a brave and injured man; so every general in the room will take a pride in signing this paper with me." This was accordingly done by Sir John Banier, the Scottish colonels, and others.
James Butler, who was then at the court of Ferdinand II., at Vienna, was stung to the soul by the tidings that his brother had betrayed a post, and he wrote to Walter a letter full of the bitterest reproaches. "You have tarnished the lustre of the Imperial arms, as well as the name of Butler," he wrote; "and Cæsar's court-martial will make your name a bye-word of reproach."
Walter Butler was grieved by this insolence and unkindness, and hastened to show the letter to the King of Sweden.
"Heed it not, Colonel Butler," said he; "send our testimonial to the Emperor, and trouble yourself no more about it."
Thirty thousand pounds' worth of plunder, and ten baggage waggons, with all the plate of the fugitives, were taken, and all their munitions of war; however, they had buried in the earth a great quantity of arms. In 1850, a labourer, when digging a trench in a field near the outworks of old Frankfort, came upon a depôt of old weapons, decaying, and covered with rust. Among them were 2000 matchlocks, being part of the munition concealed by the garrison of Count Schomberg. As soon as his wounds permitted him to travel, Walter Butler left Frankfort, for Gustavus was too generous to detain as a prisoner one whose gallant spirit was writhing under unmerited reproaches. He travelled towards Silesia, and sought out a Colonel Behem, who had commanded a regiment of German infantry at the defence of Frankfort, and to whom he was fortunate enough in tracing the first of the slanderous reports, and challenged him to single combat on horse or foot, with sword and pistol; but, awed by the justice of Butler's cause, his known skill and courage, and by the formidable testimonial of Gustavus Adolphus, he signed a full retractation and apology.