Billy Bishop goes to War explores a difficult concept in a light-hearted manner. Billy, by his own admission, is a most unlikely hero and had no idea he would make a good pilot, being expelled from military academy before his career even began. Only the outbreak of war saves him from almost certainly disappearing into obscurity. The songs in the play make Billy's sometimes ridiculous behavior seem possible. To interrupt the narrative with music that the audience can sing along to involves the audience in Billy's adventures.
The songs are an apt way for Billy to express himself in a manner with which he is familiar. The audience sees a couple of friends in a bar, having a drink and reminiscing about old times; a far cry from the stiff upper lip expected in the British military. This provides the link between Billy the man and Billy the "killing machine" and ace pilot, renowned for bringing down more planes than Albert Ball.
The songs and the non-musical element are intertwined within the life of a very naive Billy Bishop who never really stops to think about the effects of war - or his actions - "War's not the place for deep emotion." Billy hates the trenches and is glad to get away from all the mud and, if he's going to die, at least he can experience a "clean death" in the skies. The war is almost idealized as Billy focuses on the freedom of the skies. It is common for people to idealize war as otherwise it is futile and makes no sense when everyone around you is dying. The songs make provision for that, almost excusing the Military's apparent lack of concern for its men. The songs are rhythmical and the serious topics are belied by the entertaining choruses.
The music relies heavily on sounds from the piano and pianist for effect so, whilst dramatic, it is never quite real. The seriousness seems minimized against the songs and Billy too who does get melodramatic - especially when talking to Margaret - can also avoid the reality of war. There's nothing better than breaking into song to reduce tension!