med my place in the conning-tower I saw in the periscope (for
we had dived) that a lightship was within a few hundred yards of us upon
the port bow. Two men were sitting on her bulwarks, but neither of them
cast an eye upon the little rod that clove the water so close to them. It
was an ideal day for submarine action, with enough ripple upon the
surface to make us difficult to detect, and yet smooth enough to give me
a clear view. Each of my three periscopes had an angle of sixty degrees
so that between them I commanded a complete semi-circle of the horizon.
Two British cruisers were steaming north from the Thames within half a
mile of me. I could easily have cut them off and attacked them had I
allowed myself to be diverted from my great plan. Farther south a
destroyer was passing westwards to Sheerness. A dozen small steamers
were moving about. None of these were worthy of my notice. Great
countries are not provisioned by small steamers. I kept the engines
running at the lowest pace which would hold our position under water,
and, moving slowly across the estuary, I waited for what must assuredly
come.

I had not long to wait. Shortly after one o'clock I perceived in the
periscope a cloud of smoke to the south. Half an hour later a large
steamer raised her hull, making for the mouth of the Thames. I ordered
Vornal to stand by the starboard torpedo-tube, having the other also
loaded in case of a miss. Then I advanced slowly, for though the steamer
was going very swiftly we could easily cut her off. Presently I laid the
_Iota_ in a position near which she must pass, and would very gladly have
lain to, but could not for fear of rising to the surface. I therefore
steered out in the direction from which she was coming. She was a very
large ship, fifteen thousand tons at the least, painted black above and
red below, with two cream-coloured funnels. She lay so low in the water
that it was clear she had a full cargo. At her bows were a cluster of
men, some of them looking, I dare say, for the first time at the mother
country. How little could they have guessed the welcome that was
awaiting them!

On she came with the great plumes of smoke floating from her funnels, and
two white waves foaming from her cut-water. She was within a quarter of
a mile. My moment had arrived. I signalled full speed ahead and steered
straight for her course. My timing was exact. At a hundred yards I gave
the signal, and heard