ready to mend it whenever and wherever it shewed signs of want of repair. Lorries that broke down were immediately thrown off the road so that the procession might go on uninterruptedly. In this way the necessary supplies were poured into Verdun continuously for months and the valour and the military skill of our Allies did the rest. This stands out as the greatest achievement of the internal combustion engine in making motor transport one of the most important factors in the war but it is only an illustration of the services it was rendering in lesser degree in all parts of the field.
I have left the case of the submarines to the last. It would hardly be correct to say that it was the internal combustion engine that made them possible. When the French first introduced submarines they used steam, though with indifferent success, and we ourselves are using steam for certain purposes on our largest submarines of the latest type. But it is correct to say that the internal combustion engine first made them practicable.
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