The construction of two (of six) twin towers at the old
naval port of Shoreham, England.
If the war had not come to its end in 1918, boom nets would have been
hung between these sunken concrete towers, full of locally excavated
shingle, to close the gap in the English Channel to the ever presence of
U-boats, and thus blocking the remaining gap in the naval blockade of
One tower that had been completed was towed out of Shoreham harbour
for use in the Portsmouth approaches in May of 1920, becoming the famous
Nab Tower of Benbridge. Its still there to this day.