The steamer appeared to be close to us and looked colossal. I saw the captain walking on his bridge… I saw the crew cleaning the deck forward, and I saw, with surprise and a slight shudder, long rows of wooden partitions right along all the decks, from which gleamed the shining black and brown backs of horses.
“Oh, heavens, horses! What a pity, those lovely beasts! But it cannot be helped,” I went on thinking. “War is war, and every horse the fewer on the Western front is a reduction of England’s fighting power.”
U-boat commander Adolf von Spiegel relates an attack on a British steamer transporting horses. The rest can be found here, courtsey of the Independent’s A History of the First World War in 100 Moments series.