The Artilleryman Returns

Again, I was on my way to London
Through towns and villages that Were blackened ruins
Totally silent, desolate, deserted
Man's empire had passed away
Taken swiftly and without error
By these creatures who were composed entirely of brain
Unhampered by the complex systems which make up man
They made and used different bodies according to their needs
They never tired, never slept and never suffered
Having long since eliminated from their planet
The bacteria which cause all fevers and other morbidities