Article and pictures by David Flintham, all rights reserved.

Whilst over the years much has been written about the defences built to protect London during the English Civil Wars1, and even though at the time they were one of the largest urban defence systems in Europe, the fact that they have largely disappeared means that they are mostly forgotten outside specialist study.

London’s defences were developed in two distinct phases. The first, in 1642, took the form of blocking streets with barriers or chains, the building of guardhouses and some small earthworks (probably redoubts) by main roads. In addition, there is archaeological evidence for the re-use of the existing medieval defences2.

In February 1643, the defences were surveyed and proposals for a circuit of forts were presented to the Court of Common Council (the City of London’s government) by Colonel (Alderman) Randall Mainwaring. These proposals, together with a recommendation to form a Committee of Fortifications to co-ordinate construction3 were approved by the Common Council and were subsequently ratified by Parliament on 7 March 16434.

Whilst Mainwaring outlined the location and specification of the forts, he did not actually design them. Recent studies suggest that Sergeant-major-general Phillip Skippon designed the defences as he had experience of siege warfare, having been present at the sieges of Breda and Maastricht5.

Alternatively, the Venetian Ambassador, Gerolamo Agostini hinted that they may have been of Dutch design - he noted on 13 March 1643 that “they have sent to Holland for engineers”6. It was the Dutch school of military engineering that was the most readily applied, and the dominant characteristics of Dutch fortifications, namely the earth rampart and ditch, suited London’s circumstances and topography7.

By the end of March, work was well underway, entailing a massive amount of unpaid labour. Volunteers came from all walks of London life, including the Livery Companies, the Trained Bands and the Court of Common Council. At any one time, as many as 20,000, men, women and children, would be labouring on the fortifications8 and by mid-May, Agostini reported that the forts were complete9.

It is impossible to say how the defences would have stood up to attack as the Royalists never again approached London. But was defence the only purpose of the defences? Agostini certainly didn’t think so as he felt the defences were both defence against the Royalists and “against tumult of the citizens”10.

Demolition of the defences followed very closely the end of the Civil War and the Army’s occupation of London in 164711. But despite the demolition work, traces of the fortifications could still be seen for years after.

Three hundred and fifty years on, almost nothing remains of the defences and archaeological evidence is minimal, something lamented by David Sturdy in 1975 "I am sure that at least once every year for the last century and a half a section across the Ditch has been laid open. Not one has been sketched and they are gone for ever."12 However, recently archaeological investigation of the defences has taken place at New Road, Whitechapel, Peartree Street in Islington and in Museum Street in Bloomsbury13.

There is more topographic evidence and remains of forts and other features were included in a number of maps dating from the late seventeenth century onwards (for instance, John Rocque’s map of 1746 clearly shows the sites of several forts14). However, the first known map of the Lines of Communication did not appear until 1720 when William Stukeley’s British Coins included a plan showing fifteen roughly drawn forts15. The most well known is George Vertue’s plan, published in 1738, showing the Lines of Communication against a map of London. Since then, a number of historians have studied and/or mapped the Lines of Communication16.

The most useful eyewitness account is that by William Lithgow, who walked the entire 18 km circuit in a single day. Commencing at Wapping, he described all the forts then in existence and described the defences as "erected of turffe, sand, watles, and earthen work"17, 2.7m wide at its base and 5.5m high18.

According to Lieutenant-Colonel W.G. Ross, R.E., a typical dimension of civil war fortification ditches was between 2.5 and 4.5 metres across and 2 metres deep, and the supporting dike of between 2 and 2.5 metres high19. Archaeological evidence from the 1992-1994 excavation gives the dimensions of the ditch as "5.5m wide and 1.40m deep"20. This compares with other excavated civil war ditches such as Exeter (3 metres wide and 2 metres deep), Gloucester (5.5 metres wide and 2.3 metres deep), and Taunton (5 metres wide and 1.5 metres deep)21.

The defensive ditches were a mixture of dry and wet. The evidence for the latter comes from the British Library’s copy of Vertue’s 1738 plan of the fortifications upon which Cromwell Mortimer M.D., notes "The green were dry ditches. The blue were watery ditches"22. The 1992-1994 Whitechapel excavation found sufficient environmental data to support the fact that the lower part of the ditch was wet23. Its width of 5.5 metres makes this too wide to have been a drainage ditch.

Whilst masonry and brickwork was used in gateways24 and even possibly retaining walls, London’s defences were predominantly earthworks, with timber palisades and storm poles, and iron spikes. Those roads left open would have crossed the ditch by drawbridge and there would have been the additional barricades of logs and chains. What is not clear is how the Thames was guarded at the points when it breached the line (Wapping/Rotherhithe in the east and Vauxhall in the west). A chain or boom would seem likely but there is no contemporary evidence for this or for the points on the shore that would have secured such a defence.

Turning to the forts themselves, over the years a number have been studied individually. For instance, in my recent study of the fort at Whitechapel, concluded that it was a hornwork, flanked by two bulwarks.

It had a frontage of 100 metres, a depth of 55 metres, the earthen ramparts being between 5.5 and 7.6 metres high and a base thickness of 2.7 metres. It was palisaded with wooden stakes and mounted seven cannon. Positioned just to the south of what is now Whitechapel Road (formally the Essex road) between New Road and the hospital (Mount Terrace now occupies part of the site), the fort was surrounded by a defensive ditch, probably water-filled, which was 5.5 metres wide and 1.4 metres deep. Inside the fort was a timber guardhouse with a tiled roof25.

Of the forts north of the Thames, only Fort Royal (called “Strawes Fort” by Lithgow26) and Hyde Park Fort were larger, although the fort at Whitechapel was smaller than all of the forts south of the Thames. In comparison with other Civil War fortifications, Whitechapel fort is smaller than the Queens Sconce at Newark, but larger than King Charles Castle (Tresco)27.

The subject of another recent study28, Fort Royal lay outside the main circuit of defences.

Lithgow describes a very substantial, eight-angled work29, and whilst he doesn’t say whether the fort was connected to the main circuit or not, both Maitland and Vertue indicate the existence of a covered way30.

In addition to the recent studies of Fort Royal and the fort at Whitechapel, certain other forts have been studied in detail. Southampton Fort (which thanks to Roque and a late 17th century illustration is known to have a frontage of 125 metres31) has been the subject of two papers32. South of the river, the fort in St. Georges Field was described by Daniel Defoe33 and there is a good impression of a typical work in Peter Harrington’s recent book on Civil War fortifications34 From Lithgow’s description and Vertue’s map, it is clear that the works incorporated within the fortifications were of various types: sconce'(a type peculiar to the Civil Wars35), redoubt, battery and hornwork. Considering the speed of construction, the materials involved and most importantly the theoretical models of military engineering accessible and the experience of those who designed and built them, this is not surprising36.

Dependent on the source, the line of fortifications encompassed between 22 and 25 works, although 24 (plus the batteries at Mile End and Islington Pound) would seem to be the most likely number.

Following Lithgow’s route, the line ran north-westwards from the Thames at Wapping and incorporated five forts (including Whitechapel). From Hoxton, the line went south-westwards to Tyburn, with seven forts (including Southampton Fort) on the line itself and a further one ahead of the line (Fort Royal).

From Tyburn, the line continued south-westwards, then south through Chelsea and finally south-eastwards to the river opposite Vauxhall. This stretch had five works, the biggest at Hyde Park37.

On the southern side of the Thames, the line went south-westwards to Vauxhall then north-eastwards across St. Georges Fields, then eastwards via the Blackman Street fort (the largest in the chain) before heading north-eastwards to the Thames at Rotherhithe. South of the river there were six forts38.

In this account, I have attempted to provide an introduction and outline of the defences and hopefully have provided sufficient stimulus that you will want to find out more. A good starting point is Victor Smith and Peter Kelsey’s work39, and I could hardly conclude without mentioning my own contribution40 to the study.


  1. See VICTOR T. C. SMITH, “The Defences of London During the English Civil War”, Fort, Volume 25, Fortress Study Group, (1997).
  2. Ibid, pp. 65-66 and W. F. GRIMES, The Excavation of Roman and Mediaeval London, (London, 1968), page 88.
  3. Corporation of London Record Office, Journals of the Court of Common Council, Journal 40, folios 52-53.
  4. House of Lords Record Office, House of Lords Journals, Vol. 5 (18 April 1642 to 14 April 1643), p.641.
  5. SMITH, Op Cit., p. 77 and MIKE OSBORNE, Sieges and Fortifications of the Civil Wars in Britain, Partizan Press, Leigh-on-Sea, (2004), p. 85.
  6. The English Civil War - A Contemporary Account, Caliban Books, London, (1996), Vol. 3, p. 29.
  7. ANDREW SAUNDERS, Fortress Britain, Beaufort Publishing Limited, Liphook, (1989), p.72.
  8. Mercurius Civicus, 4 May to 16 June 1643, taken from JOHN JUERGEN SCHROEDER, London and the Civil Wars, University of Wisconsin, (1954), p. 251 and Perfect Diurnall of Some Passages in Parliament, May 1643, taken from NORMAN G. BRETT-JAMES, The Fortification of London in 1642/3, London Topographical Society, (1928), pp. 11 -12.
  9. Calender of State Papers, Venetian, 1642-43, Vol. 26, page 273.
  10. The English Civil War - A Contemporary Account, Op Cit. p. 33.
  11. Ibid, p. 345 and WHITELOCKE in SMITH, p. 79.
  12. Sturdy, D., “The Civil War Defences of London”, The London Archaeologist, (Winter 1975), Vol. 2, No. 13, p. 336.
  13. Greenwood, P. and Maloney, C., “London Fieldwork and Publication Round-up 1995”, London Archaeologist, Vol. 8, supplement 1, (1996) and Harrington, P., English civil War Archaeology, London, (2004), p. 27. For a summary of the archaeological investigations see Flintham, D., “Archaeological investigations of the English Civil War Defences of London”, London Archaeologist, Summer 1998, Vol. 8, No. 9.
  14. “Rocque’s Map of London, 1746”, published as The A to Z of Georgian London, London Topographical Society, (1982).
  15. “Corpus Christi College, Cambridge, MS 613”. This is reproduced in Porter, S. (editor), London and the Civil War, Macmillan Press Limited, London, (1996) and Fort no. 25.
  16. For further information see Flintham, D., “The Topography of the Lines of Communication”, in London Topographical Society Newsletter, London Topographical Society, London, (November 1997), No. 45.
  17. Smith, V. and Kelsey, P., “The Lines of Communication: The Civil War Defences of London”, in Porter, S. (editor), London and the Civil War, Macmillan Press Limited, London, (1996), Op Cit, p. 81.
  18. Smith, Op Cit., p. 73.
  19. Ross, Lieutenant-Colonel W. G., R.E., Military Engineering during the Great Civil War, 1642-9, London (1984), Plate I, p. 126.
  20. Museum of London Archaeology Services, London Hospital Medical College, An Archaeological Post-excavation Assessment, (November 1994), p. 19.
  21. Ibid.
  22. Vertue, G. Plan of the City of London as fortified by Order of Parliament in the years 1642 and 1643, (1738), Amended by Cromwell Mortimer M.D. in 1746, Kings Topographical Collection, Vol. XX, No. 16.
  23. Museum of London Archaeology Services, Op Cit, p. 19.
  24. Calender of State Papers, Domestic, Charles I, 1645-47, Vol. DXIII, p. 380.
  25. Flintham, D., “Whitechapel Mount” in Fort (to be published).
  26. Lithgow, W., “The Present Surveigh of London and England’s State”, (1643), in Ross, W. G., Military Engineering during the Great Civil War, 1642-9, Ken Trotman / Lionel Leventhal Limited, London, (1984), p. 83.
  27. Harrington, P., English Civil War Fortifications 1642–51, London, (2003), p. 58 and 60.
  28. Flintham, D., “London’s Fort Royal” in Casemate, No. 80, (September 2007), pp. 16-18.
  29. Lithgow, W., Op Cit. pp. 82-83.
  30. Smith, V. and Kelsey, P., Op Cit, pp. 132-133.
  31. Ibid., p. 133.
  32. See Weinstein, R. “Camden at War – Civil War Fortifications in Camden”, Camden History Society Review, vol. 5, (1977) pp. 21-23 and Bird, J., Chapman, H., and Clark, J. (editors), “Collectanea Londiniensia”, London and Middlesex Archaeological Society Special Papers, vol. 2 (1978), pp. 329-45.
  33. Defoe, D., A Tour Through the Whole Island of Great Britain, London, (1971), p. 293.
  34. Harrington, P., English Civil War Fortifications, Op Cit, p. 42.
  35. Lowry, B. Discovering Fortifications, London, (2006), p. 26.
  36. Osborne, Op Cit., p. 85.
  37. One flank of the Hyde Park fort survives to this day as a low embankment between flower beds and tress within the Park itself, parallel to Park Lane. Harrington, P., English Civil War Archaeology, Op Cit, p. 28.
  38. For a full description of the line of the defences see Smith, V. and Kelsey, P., Op Cit, pp. 128-138.
  39. Smith, V. and Kelsey, P., Op Cit, pp. 140-42.
  40. Flintham, D, London in the Civil War, Partizan Press, Leigh-on-Sea, (2008).

Article and pictures by David Flintham, all rights reserved.

Back to the "Fortresses" page