In August 1813, British headquarters still had misgivings about the eastern powers moving into France. Austria had now joined the Allies, but the Allied armies had suffered a significant defeat at the Battle of Dresden. They had recovered somewhat, but the situation was still precarious. Wellington's brother-in-law Edward Pakenham wrote, "I should think that much must depend upon proceedings in the north: I begin to apprehend ... that Boney may avail himself of the jealousy of the Allies to the material injury of the cause." But the defeat or defection of Austria, Russia and Prussia was not the only danger. It was also uncertain that Wellington could continue to count on Spanish support.