Like the LCI(L), the Landing Craft, Infantry (Small) originated with the concept of making long-distance commando raids. Three key differences compared to the LCI(L) were that it was smaller, was built in the United Kingdom rather than in the USA, and was made from wood. In fact the LCI(S) was the largest wooden landing craft. Like an LCI(L), troops landed by a pair of ramps, one of which was lowered either side of the bow. The ramps were easily damaged during a landing.
Above: Line drawing of an LCI(S). (Image from: Baker, Rowland, ‘Notes on the Development of Landing Craft’ in, Duckworth, A.D. (ed.), Transactions of the Institution of Naval Architects, Vol. 89. (London: Institution of Naval Architects, 1947), pp.218-258.)
The main role of the Landing Craft, Infantry (Small) on D-Day was to land Commandos, a relatively short time after the assault troops had gone ashore. Therefore it is surprising that these craft had only limited armour fitted to the sides, deck and bridge. Critically they lacked self-sealing fuel tanks, which was a significant vulnerability. Many of the LCI(S) that took part in D-Day were left badly damaged from enemy fire.