By 1875 capital warships were already developing into steam powered vessels with armoured protection and guns in rotating turrets. At about the same time a new class of warships was being introduced to various navies, the Motor Torpedo Boat. The were small but very fast and manoeuvrable allowing them to put at risk large warships.
Motor Torpedo Boats
The first British Torpedo Boat entered service in 1876, HMS Lightning, armed with two 14-inch Whitehead torpedoes. These relatively inexpensive vessels could move at 18 knots and if able to deliver its’ torpedo on target, could disable or sink a much larger capital ship. By 1885 it was fully realised that defensive measures had to be developed to counter any attack by numerous Motor Torpedo Boats (MTBs).
HMS Lightning
47mm Q.F. Gun
To counter the threat of these light, fast moving targets batteries were built mounting quick fire (QF) guns and machine guns. These Q.F. batteries were armed with guns of 12-pdr, 6-pdr and 3-pdr covering approaches to vulnerable locations.
47mm Guns
HMS Spider
At sea, larger ships were armed with batteries of Q.F. guns, so they could engage the faster moving MTBs. A new class of warship was developed, the torpedo gunboats, later Destroyers,which were designed to engage MTBs before they reached the main fleet. These Destroyers were armed with torpedoes and QF guns, for example HMS Spider had a 4-inch gun, six 3-pdr QF guns and four 14-inch torpedo tubes.
Tender ships were developed which could carry and deploy MTBs, thus increasing their operational range.
Foudre Tender
Plan of Whitehead Torpedo
The Whitehead Torpedo was invented in 1866 by Robert Whitehead and began manufacturing a 16-inch British version in 1871 at Woolwich. In 1890 production came under the control of the Royal Gun factory who too over the Royal Laboratory at Woolwich. In 1911 production of the Whitehead Torpedo switched to Royal Navy Torpedo factory in Greenock.
Portland remained as a major location for the development and testing of the Whitehead Torpedo. The Bincleaves Site was the epicentre of the Whitehead which included a short range and long range facility on the breakwater. There was also a Torpedo Depot. During the inter war years, HMS Vernon in Portsmouth took over many of the functions of the Bincleaves. There was also had a Whitehead Torpedo Factory, the Wyke Works, which developed from 1891 onwards.
Early Torpedoes
By 1900 most of the Q.F. coastal batteries had been built to protect major harbours, such as Devils Point Battery, Plymouth and New Tavern Fort QF Battery on the Thames. By 1908, with the growing prevalence of MTBs the Colonial Defence Committee issued instructions on countering attacks by flotillas of Motor Torpedo Boats operating independently. (TNA CAB 38/14). It was assumed that such MTB attacks would be on naval bases and ports (including those used temporarily).
Although MTB flotillas could operate from bases more than 300 miles away, it was suggested that they would be unlikely to travel during daylight because of the rise of interception in daylight by cruisers or destroyers. Thus, it was anticipated that any MTB attacks would be from bases within 150 miles of the friendly harbour and be conducted during the hours of darkness. The countermeasures advanced were:
- Use of breakwaters to channel traffic through choke points such as those found at Plymouth and Gibraltar
- The building of Q.F. batteries to protect the approaches to harbour or anchorage areas
- The 12-pdr QF was regarded as suitable for dealing with the small MTB but the larger destroyer and torpedo craft required a 4-inch QF gun (or 4.7-inch)
- Smaller calibre guns included the 3-pdr and 6-pdr QF, supported by machine guns.
- The sighting of Defence Electric Light for use in support of the QF guns
- 6-inch BL guns, to support the defences by firing on illuminated areas
- The use of boom defences
- Guards to be posted on lock gates and other sensitive locations to prevent sabotage
- Water patrol craft
- At location without these defences, the individual captains were to make their own arrangements
While subject to review, at that time the Colonial Defence Committee only identified Halifax, Gibraltar and Malta as needing special fixed defences to counter MTBs. Nevertheless QF batteries where built in nearly all major naval ports overseas, often in support of minefields and boom defences.