In 1801, while fighting the French in Egypt, Sir George Murray and his men found themselves in desperate need of water. From his classical education, Murray knew that Julius Caesar had once faced the same dilemma in virtually the same spot (just outside of Alexandria).
Murray promptly consulted a copy of Caesar's writings (which he always kept with him) and was happy to discover that the Romans had indeed discovered water at a certain depth. Murray's men dug wells in the sand -- and soon had more water than they knew what to do with.
Sources
W. Keddie, Literary and Scientific Anecdote
