Of the many small forts and gun batteries built along the coast of Southern England during the past few centuries only two survive in anything like there original form, Littlehampton fort, completed in September 1854 (now largely covered by the sand dunes) and Shoreham fort, also know as Kingston Redoubt, completed in June 1857, both of which are in West Sussex.
Both these forts are especially important examples as they were built as experimental fortification, using what is known as a Carnot Wall. These were built directly after the introduction of the 'rifled' gun barrels on the continent, rifled barrels were an invention of the mid-nineteenth century with the aim and succession of increasing the range of heavy guns, they are also a form of fort from the nineteenth century not exhibited in the near contemporary, but slightly later in the forts protecting Portsmouth Harbour, in Hampshire.
After several centuries of the harbour at Shoreham being classed as insignificant it increased in importance as that of the neighbouring Sussex ports declined. The defenceless state of Shoreham harbour 
was of small concern until well into the nineteenth century. In fact there were several reasons for this. The mouth of the river Adur was shifting eastwards due to it silting up. In 1810 the mouth was situated almost opposite Aldrington church, close to the Hove border. An army could be found in other places around Sussex , where it was said to be more convenient for an invasion army to disembark, being closer to the French coast and further away from the army detachments encamped, usually in Brighton . For many years Brighton was considered as being a premier military station. The social life in Shoreham town was attractive to the officers, so regular manoeuvres were held on the, nearby, south downs, usually annually.
One good example of why there should have been defences and why, probably, the fort was built is confirmed by an incident in 1628. Some French ships navigated their way into Shoreham harbour, whilst in the harbour they managed to capture a small craft. Without any sort of defence at the time, the attack caused great alarm and commotion and men were dispatched to Brighton to fetch ordinance, fearful of any further raids. It seems there was, at the time, no artillery nearer than Brighton, which I feel proves the need and reasoning for building the fort, it also explains why the south coast was defended so well, having forts and gun batteries built at regular intervals.
During tensions in the Napoleonic period, new batteries were built at Bognor, Selsey and other previously unfortified places. But still Shoreham was left defenceless and no special preparations were thought necessary to build defences at that time, although in 1801 500 troops were deployed to defend or even destroy, if required, the Adur Bridge , then situated much further up river near the Sussex Pad Inn.
In 1816 the wandering exit of the river Adur was finally stabilised between two piers in the same positions they are today. This then helped increase the trade and commercial use of the harbour. So in the 1850's when French intentions caused apprehension, it was then apparently decided to man and defend the harbour mouth, with a permanent fort so the newly constructed harbour entrance, as it was then, was the selected site for Shoreham Fort, just on the wide spit of shingle immediately to the west. This was so that the guns could defend and command the harbour entrance, its approaches and the beach.
Work began on the fort early in the year of 1857 and in June 1857 the fort was completed and details of cost, armament and accommodation are given in a record drawing of Shoreham Redoubt, drawn from some old plans and measurements by W. Mumford, of The Royal Engineers, on the 1st September, 1886. The estimated cost was £10,000 and the actual cost was £11,685.10s.0d. This was more than the fort at Littlehampton, but it was slightly bigger as it was built to include six guns instead of five and the ditch defences were more elaborate. An anonymous note in Brighton reference library ( Box 24 ) gives the builder Messrs. Smith of Woolwich, but the source of this information is still unclear.