The concept of women in combat is not a new one. Brave female warriors have fought and died for their country since time began. In 61 AD, Boudicca, queen of the Iceni people of Eastern England, successfully led a major uprising against the occupying Roman Ninth Legion, destroying the capital of Roman Britain. Then there were the Trung sisters, the fearless daughters of a warlord who led Vietnam's first national uprising against the Chinese in the year 40 AD. Many others followed in their footsteps in the years to come.

And yet, women serving on the front line is still a contentious issue. The UK has only just started to move towards revising its ban on women in front line close combat roles (we cannot currently serve in Household Cavalry, Royal Armoured Corps or Infantry), following the lead of the US, which lifted similar restrictions last year. Canada, Denmark, Finland, Germany, New Zealand, Norway, Poland, Romania, Spain and Sweden all permit women in combat units, while many other countries, including Britain, send women to the front line in non-combat roles, or allow female pilots.

The women we profile here clearly illustrate that gender is no barrier to valour. Whether they're mothers or daughters, sisters or wives, they've all taken up arms and responded with bravery and composure in a time of need. And while you may not agree with all of their causes or actions, there is no denying their inherent courage and strength in the face of chaotic, bloody scenes of conflict.

Come salute just a few of history's greatest female front line heroes:  

Not for Flora Sandes the respectable Edwardian woman's pursuits of knitting, tennis and tea parties. As a Suffolk-born tomboy, Flora envied her brothers and "used to pray every night that I might wake up in the morning and find myself a boy". When war broke out in 1914, the 38-year-old travelled to Serbia as a volunteer in the British ambulance service. She performed surgery and ran a military hospital there but when the Bulgarian army invaded in 1915 she was given the choice of either retreating with the field hospital or joining up.

Flora did not hesitate and quickly became indispensable in her role as a soldier with the Serbian army - the only Western woman known to have held such a role during the Great War (the Serbian army was one of the few of its kind to accept women recruits at the time). She rose swiftly through the ranks, becoming Corporal, then Sergeant-Major. In one incident, she was wounded by a grenade during hand-to-hand combat and had to be rescued by a colleague who crawled out under fire to save her.

The explosion left her with shrapnel embedded in her back and the whole of the right side of her body but in 1917, she was awarded the Serbian army's highest military medal for her bravery under fire. When she recovered, she re-joined her men in the frontline trenches and received a warm welcome from her fellow comrades.  "They called her a 'brother', as as an honorary man," says Flora's biographer Louise Millar. "She was a good solider... Serbia was the only country that allowed women to do anything they wanted during the war. They had more freedom than anywhere else partly because the Serbians didn't know what to make of these women and their need was so desperate."

After playing a central role in the Great War, Flora joined up once again, aged 65, at the outbreak of World War II in 1949. She was imprisoned by the Gestapo and after the war, moved to Rhodesia - now Zimbabwe - where she scandalised the colonial classes of the time by drinking and smoking with the local black population, according to the Mail.

She says: "[Of the army] I never loved anything so much in my life. I felt neither fish nor flesh when I came out of the army. The first time I put on women’s clothes, I slunk through the streets."

Tyneside army medic Sarah Bushbye was awarded the Military Cross for bravery after she dodged incoming fire from insurgents in Afghanistan to attempt the rescue of four of her colleagues. The 25-year-old Lance Corporal was on patrol with the 3 Rifles Battle Group in December 2009 when her checkpoint came under attack by two suicide bombers. Ignoring the risk to her own life, she dashed across 500 metres of open ground to a group of Afghan and British soldiers. Amid enemy gun and rocket-propelled grenade fire, she administered CPR and help transport the injured troops to a Chinook helicopter.

The Army citation for L/Cpl Bushbye’s Military Cross says: “Ignoring the bullets cutting the air about her, she calmly moved between each casualty, determined to do all she could to care for them. The weight of enemy fire increased. With flagrant disregard for her own safety, Bushbye nevertheless continued to move between the casualties, personally administering CPR to one of the soldiers. Bushbye crossed the bullet-swept ground between the checkpoint and the helicopter repeatedly, throughout working desperately to keep the men alive.”

The soldiers eventually succumbed to their injuries but L/Cpl Bushbye’s courage in the situation went far beyond the call of duty. She became only the third woman to receive the Military Cross, which recognises "an act or acts of exemplary gallantry” and is presented by the Queen.

She says: “It was like a horror movie. It was very busy and it went on for about an hour. But it’s all about your training. If you get good training you can get through just about any situation. I was nervous coming up to the scene, but when I was at the scene I forgot about everything and just did my job. When we were back at the camp that’s when it sort of hit you, it was quite an emotional evening because we lost our two guys. I don’t see myself as any hero, I was just doing my job but it is an honour to be awarded the Military Cross.”

Ngo Thi Tuyen was one of the many women who served in the militia with the North Vietnamese Army during the Vietnam War. She became a national hero thanks to her actions during the defense of Dragon Jaw Bridge, a strategically crucial north-south infrastructure that came under attack from an American-led air raid in April 1965.

A recently married peasant woman, Tuyen was plunged into action when the assault began, along with many of her neighbours from the nearby NamNam village. Throughout the day and night, she and her comrades withstood shelling and aerial bombardments on the bridge, suffering devastating casualties along the way. A total of 22 local women, many of whom were high school graduates, died that day and Tuyen watched them perish. "More than once my strength came from anger and the need to avenge my dead comrades," she later said.

Tuyen shouldered 95 kilograms of anti-aircraft artillery shells (more than double her body weight) that she ferried to soldiers in trucks heading south. When a Western journalist later questioned her feat, she recalled how she proved him wrong. "He didn't believe that such a small person like me could shoulder such a heavy burden," she said. "I persuaded him by picking up a sack of potatoes and a sack of rice that together had a total weight of 105kg."

Tuyen was also a trained anti-aircraft gunner and part of her responsibilities included tracking any US pilots who bailed as their planes were downed, in order to gather intelligence from them. After the war, Tuyen served as a Lieutenant-Colonel in the regular Vietnam army but was plagued by long-term back problems as a result of her actions during the war.

She says: "We had to defend the Dragon's Jaw Bridge at all costs on that terrible night - and we had to keep the trucks going over it on their way to the south. I don't know why I was able to carry those big boxes of ammunition. But at that time, my only thought was that our soldiers were in need of equipment to shoot down the bombers."

Mariam Al Mansouri is the UAE’s first female fighter pilot. The 35-year-old Captain hit headlines recently after she led coalition airstrikes against Islamic State (Isis) in Syria. Al Mansouri is a squadron commander and flies a F-16 Fighting Falcon, a single-engine multirole fighter aircraft. She wanted to fly fighter jets ever since she was a teenager and spend several years working at General Command before the UAE relaxed its ban on women joining the military service in 2007.

With backing from her family, she joined the UAE Air Force and has since taken part in a number of aerial deployments both inside and outside the UAE alongside allied forces. She has been awarded a number of medals for her services, including Dubai’s Mohamed Bin Rashed award for distinguished governmental performance.

Yousef Al Otaiba, the UAE’s ambassador to the United States, last month confirmed that Captain Al Mansouri was involved in the coalition strikes against Isis in Syria.

“I can officially confirm that the UAE strike mission… was led by female fighter pilot Mariam Al Mansouri,” he said.

“She is a fully qualified, highly trained, combat-ready pilot and she is on a mission.”

She says: "Everybody is required to have the same high level of combat competence [in the UAE Air Force]. It is a time and effort-consuming field that requires a great deal of passion."

Cathay Williams was the first documented black woman to enlist in the US Army, a feat she achieved by posing as a man. Cathay was born into slavery in Independence, Missouri in 1842. When the Civil War broke out in 1861, she was freed by Union soldiers but was forced to become a servant as part of the Federal army. Aged 17, she travelled across the country and witnessed many battles, including Shenandoah Valley raids in Virginia.

She knew then that she wanted to become a soldier and when the war ended, she enlisted under the name William Cathay. At 5' 9'', only a cursory medical check was required to be recruited and Cathay passed the test undetected, becoming a Buffalo Soldier - the name given to African American regiments in the US Army at the time - on November 15, 1866 in St. Louis. She travelled on garrison duty with the 38th U.S. Infantry across Missouri, Kansas and New Mexico. Only her cousin, who served alongside her, knew her true identity.

The truth was finally revealed when Cathay was struck down with smallpox in 1868. Her post surgeon revealed to her commanding officer that was, in actual fact, a woman and she received an honourable discharge from the army. She suffered from illnesses on and off afterwards, and even had all of her toes amputated after suffering from diabetes. But because she had not legally been a part of the Army, she was refused any type of pension, disability or otherwise. In 1876, she gave her story to the St. Louis Daily Times.

She says: "I wanted to make my own living and not be dependent on relations or friends... The men all wanted to get rid of me after they found out I was a woman. Some of them acted real bad to me."  

Sgt. Leigh Ann Hester became the first woman soldier since World War II to be awarded the US Silver Star medal after she fought her way through an enemy ambush in Iraq in 2005. The 23-year-old Kentucky native was shadowing a supply convoy with her unit, the 617th Military Police Company, when it came under fire from a group of around 50 insurgents armed with assault rifles and rocket-propelled grenades in March 2005.

Hester "maneuvered her team through the kill zone into a flanking position where she assaulted a trench line with grenades and M203 rounds," according to the army citation which marked her Silver Star.

"She then cleared two trenches with her squad leader where she engaged and eliminated three AIF [anti-Iraqi forces] with her M4 rifle. Her actions saved the lives of numerous convoy members,"

Six other soldiers from Hester's squad won awards for defeating the ambush, which left 27 insurgents dead, six wounded and one captured.

She says: "It really doesn't have anything to do with being a female. It's about the duties I performed that day as a soldier. Your training kicks in and the soldier kicks in. It's your life or theirs. You've got a job to do - protecting yourself and your fellow comrades."

Zoya Kosmodemyanskaya was just 18 years old when the Nazis invaded the Soviet Union in 1941. The authorities were looking for guerrilla activists to disrupt the German army's advance as much as possible and Zoya readily volunteered despite her young age. As part of the Red Army Western Front, she was given the code name Tanya and was trained to use a revolver before being sent out on her first task - to lay mines on the Volokolamsk highway, just behind German lines.

The mission succeeded and Zoya petitioned for a more dangerous role, of the kind that were usually reserved for the group's male activists. "Difficulties ought to be shared equally," she pleaded to her commander, who eventually agreed and sent her on an assignment to Petrischevo, a village brimming with German soldiers. Her orders were to burn down a house and a stable, which she did, but she was spotted by a villager and reported (some reports also suggest she was betrayed by one of her comrades who had been captured).

The next day, she returned to the village and was immediately captured by German forces. She underwent horrific torture in a bid to find out who her collaborators were but she refused to give any information. "The young Russian heroine remained tight-lipped. She would not betray her friends. She turned blue with the cold, blood flowed from her wounds, but still she said nothing," a German sergeant who was present at the scene later recalled.

The next day, Zoya was publically hanged with a sign reading "arsonist" hung around her neck. After the war, she was posthumously made "Hero of the Soviet Union" with novels, plays and films dedicated to her.

She says: "If we fall, let’s fall like heroes"

Captain Ashley Collette was awarded Canada's Medal of Military Valour for her work leading a platoon of soldiers on a dangerous deployment to Afghanistan in 2010. The only woman in her group of 60 men, from the First Battalion of the Royal Canadian Regiment, the 26-year-old supported her troops as they faced twice daily attacks from insurgents in the remote town of Nakhonay, near Kandahar.

Every day for months on end, whether out on patrol or back at their camp, the platoon came under attack from machine gun fire, roadside IEDs (Improvised Explosive Devices) and suicide attacks in what the soldiers began to dub "contact o'clock". Not far into their deployment, the battalion suffered its first casualty when a soldier was killed by a bomb while out on a foot patrol.

"We still had six months to go," Capt. Collette told the BBC. "I remember thinking 'How am I, one, going to hold it together myself, and two, going to hold together this group of 60 people who are devastated by this event?'"

But she did manage to hold it together and when she returned to Canada, she was awarded the Medal of Military Valour for her fortitude and performance under pressure, which was key to disrupting insurgent attempts to recapture the crucial area.

"We honour today your bravery in the field, your actions which directly enhanced the safety of your comrades-in-arms," said Governor General David Johnston, as he presented the honour. "Yet, I would be remiss if I did not also honour how you have defended the ideals that we hold dear and how you have helped to promote peace, sometimes by the strength - by the virtue - of your character alone."

She says: "In my experience, there's no reason why a band of brothers cannot be a band of brothers and sisters."

Army surgeon Dr. Mary Edwards Walker was the first and only woman to be awarded the Congressional Medal of Honor for her work during the American Civil War (1861 – 1865). A tough and outspoken female rights activist, she never played by the rules and drew taunts growing up because of her penchant for wearing men’s clothes, including trousers and starched collar shirts. "Boys chased her and threw rocks at her," recalls her biographer Sharon Harris. "She once said that nobody would ever know what she had to go through just to step out the door each morning."

Dr. Walker studied at Syracuse Medical College – the first of its kind in America – and when the Civil War broke out in 1861, she travelled to Washington DC and demanded a place in the Union Army. Her application to become a medical officer was rejected but she volunteered as a nurse, and later on as a surgeon, nonetheless. She travelled around treating the wounded on the bloody battlegrounds of the Union frontline for nearly two years.

In 1864, Dr. Walker was captured by Confederate troops and kept as a prisoner of war in Virginia for half a year. There were rumours that she was working as a spy during this period, to transport intelligence on the Confederacy back to the Union.

After the war was over, Dr. Walker still campaigned for a role in the US army. She was refused but instead awarded the Medal of Honor which noted that she had "devoted herself with much patriotic zeal to the sick and wounded soldiers, both in the field and hospitals, to the detriment of her own health. She has also endured hardships as a prisoner of war for four months in a Southern prison."

In 1917, her medal was rescinded along with others, when the terms used to designate the award were reappraised. But she refused to stop wearing it and in 1977, thanks to a campaign on behalf of her family, the honour was posthumously restored.

She says: "You men are not our protector... If you were who would there be to protect us from?"

Please note: this is just a snapshot of the female fighters on the front line - there are many more we haven't included. Feel free to add your own suggestions in the comments section below. Photos: Getty Images and Rex Features.