The fighting machine shield was made for George Pal's version of The War of the Worlds. The shield, which was dome-like in apperance, was invisible until something struck it. The shield was probably electromagnetic, as the heat ray and skeleton beams could pass through it untouched. Steven Spielberg put this in his 2005 blockbuster, with similar descriptions as George Pal's movie. Eventually bacteria rendered the shields useless, and the fighting machine was destroyed.