With multiple countries currently in conflict with each other, the prospect of a world war can be a scary thought. However, if WW3 was to happen, there could be some professions deemed as too crucial to the security of the UK to be permitted to fight on the front lines. While no formal outline into how conscription would be like in this day and age has been revealed, how individuals were signed up for the war effort in WW1 and WW2 may be something to look into. Many men fought for Britain during the Second World War, with a large number of women also providing support to the war effort in a range of ways. READ MORE: Nuclear war expert warns over safest countries if WW3 began Those who were involved in providing food for the nation, such as the bakers, farmers, doctors, nurses or engineers had a crucial role, which often meant they were spared from fighting in the war, YorkshireLive reported. There was also a category for those know as 'conscientious objectors'; individuals who were sent to tribunals and forced to work in roles which were not directly associated with combat, which were said to aid the war effort in alternative ways. During the Second World War, conscription commenced around six months before the war actually began, with men aged between 20 to 22 the first on the list in 1939. The UK Parliament website says: "During the spring of 1939 the deteriorating international situation forced the British government under Neville Chamberlain to consider preparations for a possible war against Nazi Germany. "Plans for limited conscription applying to single men aged between 20 and 22 were given parliamentary approval in the Military Training Act in May 1939. This required men to undertake six months' military training, and some 240,000 registered for service." Once war was declared, the age group of those required to sign up was made larger, with any person between 18 and 41 who wasn't "medically unfit" required to serve the country. Parliament information adds: "On the day Britain declared war on Germany, 3 September 1939, Parliament immediately passed a more wide-reaching measure. READ MORE: The hidden base dubbed 'one of safest places on earth if war broke out' - and it's only an hour from Birmingham "The National Service (Armed Forces) Act imposed conscription on all males aged between 18 and 41 who had to register for service. Those medically unfit were exempted, as were others in key industries and jobs such as baking, farming, medicine, and engineering." Two years after the war had begun, in 1941, women and those classed as 'childless widows,' between the ages of 20 and 30 were required to provide support. The age group for men who had to fight had also expanded by this point, with those up to 51 expected to join the military effort. Men even older than this, in the 52 to 60 category, were also required to take part in 'some form of military service'. The website added: The main reason was that there were not enough men volunteering for police and civilian defence work, or women for the auxiliary units of the armed forces." Mike Martin, an Afghanistan veteran and the MP for Tunbridge Wells, told the Express: "There's a significant chance that it [war with Russia] might happen so we must be prepared. "Obviously, if we get involved in a general war with Russia, we'll be conscripting the population - there's no question about that," "Being prepared generates deterrence, which decreases the likelihood [of war]. The whole point about building the military up is it decreases the likelihood of this happening. I think that's an important caveat. I've fought in wars, I'm not a warmonger. But I recognise that you've got to [pursue] peace through strength."