Original sentence: Soon afterward, the Luftwaffe's chief of staff, Karl Koller, arrived with unexpected news--Hitler, who had by this time conceded that Germany had lost, had suggested that Göring would be better suited to negotiate peace terms
Edited sentence: Soon afterward, the Luftwaffe's chief of staff, Karl Koller, arrived with unexpected news—Hitler, who had by this time conceded that Germany had lost, had suggested that Göring would be better suited to negotiate peace terms