In 1793, the French Revolution reached its climax when the Revolutionary Government issued orders to execute King Louis XVI and Marie Antoinette.
To prepare for invasion in 1794 British Parliament purchased a large piece of land at Shorncliffe, the obvious place for initial fortifications to be built as it was just 20 miles away from the French coast, so close, in fact, that the locals could see the smoke from the camp fires of Napoleon's waiting army.
[1] Later further defences were added to the Kent Coast including the 28-mile-long Royal Military Canal, started in October 1804 and finished in June 1805, which stretches from Cliffend to Seabrook.
It is surmised that the turfs were then placed at the bottom of the mound to create extra stability and to promote growth of the grass for protection from the weather.
It turns out that the maps were more guidelines for the construction of a much larger star fort which was never built due to the change of infantry tactics brought forward by Colonel Coote Manningham and Sir John Moore.