 Complete the following phrase:  Traditionally some historians have considered the air forces of the First World War to have had relatively little direct effect on events on the ground with their CAS and tactical bombing efforts. It is certainly true that the effect of ground attack units during this period was not as great as it was during the Second World War, where ground attack aircraft could have a devastating effect on ground forces. For example, during the attacks launched by the air forces of the Second World War Allies on German troops in the 