In World War I, cavalry warfare gave way to primitive tanks for the first time. The British had the first tanks, but their manganese-steel plates couldn't take the full shock of a shell. Fortunately for the Brits, their ally, France, had created molybdenum-steel armor plating that could provide better protection at one-third the thickness. This WWI tank sits in London's Imperial War Museum.
Molybdenum has an exotic connection as well: A Russian mission called Luna-24 turned up a minute particle of nearly pure molybdenum on the moon, the first time it had been located there.