Legally, French armed civilian resistance, after their Government had surrendered in June 1940 was terrorism. Under the very specific rules of warfare and its legal issues the Germans were correct.
That's why I said: "This action [by SNCF workers + SOE] was literally 'criminal' and subjectively 'terroristic' to German High Command and forces."
The Germans were perfectly within their rights to execute French workers who indulged in sabotage that assisted the Allied war effort. Whether summary excecution is legal is maybe another matter. Without doubt though taking 10 or in some cases 100 of the local population off the street at random and executing them as a reprisal for each German soldier killed by partisans was definitely illegal, not to mention the 690 or so men, women and children who were unlucky enough to be in Oradour Sur Glane that June day. Taking what the resistance was doing as 'asymmetric warfare' though, even that aided the Allies - the Waffen SS being stupid enough to waste half a day murdering civilians added half a day's extra delay to their arrival in Normandy.
Pine Marten is correct when he says terrorism is about 'semantics' that being literally the interpretation of the meaning of words. 'Terrorism' is one of these emotional catch-all words that in media and common useage covers a spectrum of activities from a focussed form of criminality such as the ALF and Huntingdon Laboratories through to Dr Goebbels branding all RAF bomber crews as 'Terrorflieger'. The 7/7 bombers and before that the Provisional IRA campaigns in both Ulster and the UK mainland were often so described, but in the eyes of those carrying out these activities, they were fighting a war, they were and some still see themselves now as soldiers. If they weren't, why did we retain five or six army battalions on top of NATO and other requirements thanks to the IRA? (I once said I hoped the early Ulster peace process would be sucessful to an Army WO and a veteran of three Irish tours that I occasionally shot with - he was appalled and said he hoped 'the troubles' would continue indefintely and put me firmly in my place.)
Whether we like it or not, whether we call it other things, we are now engaged in asymmetric warfare against a tiny minority of our own citizens. I worked in London throughout the mainland IRA campaign commuting daily by rail, and was close enough to the Hyde Park bandstand bomb to feel a tiny part of the pressure wave as well hear it. Everybody who travelled in and out of London and used the tube knew that we were involved in a conflict - the use of heavy curtains kept drawn over many railway building windows to stop glass fragments in the event of an explosion reminded you on a daily basis, not to mention the number of times I walked from Paddington to Kings Cross with the tube shut down for security scares, mostly hoax or carelessly left but innocent packages.
Publicly calling countering domestic Islamic insurgency a war and trying to use non specialist soldiers as we did in Ulster are probably unwise as it is a 'war' of intelligence and security service / police work and arrest. Still, the recent major London security exercise involving special forces amongst others shows that a Mumbai style attack on London by determined men armed with rifles and grenades who know they will sacrifice their lives is taken very seriously, and needs an at least partly military response.
The number of active IRA 'soldiers' was always small, the numbers of supporters was larger but still modest, so one doesn't need huge numbers of lethal fanatics to cause great damage and disruption. We have a small percentage of the Muslim population who support the dangerous fanatics, and any country which takes on board a large increase in so-called Syrian refugees which includes an increasing number of Balkan people and those from a whole range of dysfunctional North African states as well as other non Syrian middle eastern countries, such as the 800,000 Frau Merkel says she'll take this year and the up to 500,000 pa for the next few years, will get a percentage of those who want to change their adopted countries and societies radically, and if the natives don't agree, do so by force. It doesn't matter whether the would be armed Jihadis are 1% of the influx (seems far too high or 0.0001%) when you're talking literally millions you're going to get a few hundred very dangerous people indeed and a good few thousand supporters giving safe houses, funds, carrying and hiding weapons.
And we will get them. It doesn't matter how many people on this and other forums argue either way about accepting or rejecting these people, we are going to see unprecedented people movements into Europe, unless the Hungarian razor wire fence and 'non lethal force' by police and military is replaced by 'Fortress Europe' and armed guards who will use lethal force, a new version of the old Berlin wall and East / West German border in GDR days, with its hundreds of miles of wire, minefields, cleared areas, watchtowers, and automatic tripwire activated machineguns. And it doesn't matter a damn if we stay out of Schengen as once Frau Merkel gives them German passports, a fair number will quite legally come here, most with good intentions, a tiny minority with very bad ones.
People say Europe coped with the huge DP flows in 1945. Apart from the fact that WW2 killed over 30 million people across Europe creating rather a lot of 'space', there were VERY much smaller indigenous populations in each country before the catastrophe occurred. Germany had a 19139 population of 69.3m compared to 82.6m now; the UK was 47.7m; a shade under 60m today. Moreover, the vast majority nof DPs didn't want to settle anywhere new, they wanted to and mostly succeeded in getting back to their prewar countries. And in fact many who didn't want to return had no choise seeing as how our armed forces amongst others were used to repatriate thousands of Soviet citizens to the USSR literally at bayonet point at the railheads, many of whom faced the gulags at best, torture and execution at worst.