Meanwhile, the expansion of the Habsburg dukes in Swabia collided with the growth of the Old Swiss Confederacy and sparked armed revolts. In 1386 Duke Leopold III and numerous Austrian nobles were killed in a disastrous defeat at the 1386 Battle of Sempach, whereafter Albert once again became sole ruler over the Albertinian and Leopoldian lands, acting as regent for his minor nephews. Another attempt to restore Habsburg rule in Swabia failed, when Albert's knights were again defeated by the Swiss pike squares in the 1388 Battle of Näfels and the duke had to call for an armistice.