The pictures on this page, are in order, from top to bottom, and if they are by each other, left to right.  
1 My picture of Tre'r Ceiri, nobody can use that pictures without my permission, 2 Engraving of Cadbury Castle, drawn in 1723 by William Stukeley and captioned "Prospect of Camalet Castle" I found that on Wikipedia Public Domain. 3 A pic by me from Caer Drewyn Hillfort, near Corwen, inland North Wales. Looking from the ancient walls here, nobody can use this picture without my permission, more on this site on other pages, but it is a Iron Age hillfort.  4 A pic I took of Burnswark Hillfort, southern Scotland, near Gretna, nobody can use it without my permission. 5 A picture I found on Wikimedia Commons, Gate Pā after its evacuation on 30 April, based on a sketch by Lieutenant Gordon Robley, Created: 1 January 1864. New Zealand's Maori Pa sites, had strong similarities to hillforts so I show them here symbolising the most modern equivalents of hillforts, in picture form. 6  Then to the right of there some of the eastern ramparts of Penycloddiau, again a picture from me so you would need permission for me to use it. This the largest hillfort by area in Wales, and sits on the Clwydian hills, a north south hill range, notable for it's long line of hillforts. You can see why the term in for it in Welsh, is actually translated into English as the Hill of ditches. 7 A map I found on Wikimedia commons of where certain hillforts are in Britain indicating the plenitude, and numerousness of forts in Britain, though for any map like this it depends on what you regard as a hillfort, most also include promontory forts, as I do, but some wonder if some smaller sites should not be counted in the category, which is a debatable point. 8 A composite of a public domain picture of a hillfort, depiction I  adapted so it is now my pic, plus a public domain picture of some Celtic Soldiers, so now it can only be used as this adapted version with my permission. I have to admit the Celtic soldiers costumes were early 20th Century imaginings, so they may are not fitting totally with modern views, but it is better than nothing. 9 A picture I took from the hillfort above Holyhead, of it's ancient walls, looking down on the sea. 10 The final picture on this page.  Well there are no pictures of Iron Age hillforts, I know of from the times they were in action. There are descriptions of a sort, in Roman literature of the time, and to a extent from the Irish Myths from the Dark Ages. What I see as a similar site is what is depicted on Trajan's Column, When the Roman army with great planning and fortitude conquered Romania's Dacians, with during their battles them facing upon Barbarian hill top settlements. Well their attacks are commemorated on Trajan's Column, built on order of the said Emperor in 107-113AD. The Dacian sites must have had some similarities to hillforts, although they were economically a more advanced society than Britain's Celtic tribes of the time, them being near the economic centre of the world at the time. Not that Britain's Celts were not of some level of advancement in their own way. So this scene could be said to have some similarities to a attack on kind of some hillforts, but maybe more so, the Iron Age French Oppida, which were the kind of more advanced giant versions of hillforts, at their largest on the continent. There would be some similarities to some hillforts in Britain, and therefore all, as they all shared to some extent a common set of origins, I would say.  The statement in Wikimedia Commons is, The advance-guard in action (scene LXX); storming of a Dacian fortress (scene LXXI), Conrad Cichorius, 1896 plates.