Despite its belated use of advanced turbojet and rocket propelled aircraft for the destruction of Allied bombers, the Luftwaffe was overwhelmed by the Allies' superior numbers and improved tactics, and a lack of trained pilots and aviation fuel. In January 1945, during the closing stages of the Battle of the Bulge, the Luftwaffe made a last-ditch effort to win air superiority, and met with failure. With rapidly dwindling supplies of petroleum, oil, and lubricants after this campaign, and as part of the entire combined Wehrmacht military forces as a whole, the Luftwaffe ceased to be an effective fighting force.