In the 1870s, it became obvious that the then senior branch of the ruling House of Welf would die with Duke William. By house law, the House of Hanover would have ascended the ducal throne. However, the Hanoverians still refused to accept the Prussian annexation of their kingdom. As a result, Prussia was unwilling to let George V of Hanover or his son, Ernest Augustus, succeed to Brunswick. Berlin would only agree to the Hanoverians becoming dukes of Brunswick under severe conditions, including swearing allegiance to the German constitution and renouncing all claim to Hanover.