Gallas's "ineffectiveness severely damaged the Habsburg cause in the latter stages of the Thirty Years’ War". His army had earned for itself the reputation of being the most cruel and rapacious force even in the Thirty Years' War, and his "Merode Bruder" have survived in the word "marauder". Like many other generals of that period, he had acquired much wealth and great territorial possessions (the latter mostly his share of Wallenstein's estates). Although Gallas was victorious in the first of the battles of Nördlingen (1634), carelessness and drunkenness thereafter marred his conduct of the war. He later became known as the “destroyer of armies,” especially after his disastrous campaigns of 1637, 1638, and 1644, each of which resulted in the annihilation of his troops.