In the centre of London, close to the statue of Gandhi and the Hiroshima blossom tree, there lies another testament to the futility of war.
Unlike memorials in many towns and villages, there is no statue of a soldier or testament to "our glorious dead" above the inscription.
But this understated lump of volcanic rock in Tavistock Square will become the focus of a world-wide movement, which today marks International Conscientious Objectors' Day. This year the emphasis is on conscientious objectors and GIs who want to leave the US military over the war in Iraq, and there are events scheduled for New York and Washington DC. British conscientious objectors will mark the day with their own memorial to remember the thousands of people worldwide who have suffered and died for the right to refuse to kill.
"As the war in Iraq drags on more people are starting to question what is happening and recognise the need to stand up for peace," said Bill Hetherington of the Peace Pledge Union, which plans to read out a list of names, one for each of the 68 countries where there have been conscientious objectors, at a memorial service today.
It was not until the First World War that the term conscientious objection was recognised. "Conscription was introduced in 1916 to replace the thousands of men who had already been killed, and more than 6,000 men went to prison because the Government refused to recognise their beliefs," said Mr Hetherington, who has spent years compiling a database of every British conscientious objector.
"A lot of those men suffered terribly or even died for refusing to fight. They shouldn't be forgotten."
Although the Government agreed to a "conscience clause" in the 1916 Conscription Act, which gave the right to claim exemption from military service, out of more than 16,000 men who applied, only a handful were successful.
Conscientious objectors fell into three categories - "absolutists", opposed to any form of military service and anything which helped the war effort; "alternativists" who were prepared to undertake alternative civilian work free from military control; and "non-combatants" who were prepared enter the military in a non-combat role. If the men failed to get an exemption they were liable to be drafted or arrested and punished.
There was little sympathy among the public. Although about 3,400 conscientious objectors accepted call-up into the Non-Combatant Corps, which the press dubbed the No Courage Corps, or the Royal Army Medical Corps, other men, who regarded themselves as absolutists or alternativists, who were forcibly enlisted were often bullied, deprived of basic rights, and imprisoned if they refused to obey orders.
It is estimated that more than 6,312 conscientious objectors were arrested; 5,970 were court-martialled - some were sentenced to death but had their sentences commuted before being sent to prison. Other conscientious objectors were sent to work in camps, set up by the Home Office, where they were forced to make fertiliser from dead animals or do back-breaking manual labour for non-existent projects.
At a camp at Dyce, near Aberdeen, about 200 men were forced to quarry stone while living in leaky tents with poor sanitation, little food, and no medical attention. One man, Walter Roberts, died and became the first of 73 conscientious objectors across the UK to lose their lives as a result of their treatment.
By the time the Second World War started, the number of conscientious objectors had risen from 6,000 to 61,000, yet society still often regarded them as "cowards, selfish, irresponsible, pro-Nazi and dangerous to society". Out of the 60,000-plus who claimed to be conscientious objectors less than 3,000 were given unconditional exemption from military service and about 18,000 were turned down altogether as not "genuine". The remainder were allocated to essential civilian work such as farming or forestry, or drafted into the military in non-combat roles including dangerous jobs such as bomb disposal.
By the end of the war, about 5,000 men and 500 women had been charged with offences linked to conscientious objection, and most were sent to prison.
After the war, conscientious objectors continued to oppose National Service and refused to fight in conflicts in Malaya, Korea and Suez.
In 1987, the United Nations Commission on Human Rights recognised "the right of everyone to have conscientious objection to military service as a legitimate exercise of the right of freedom, thought, and religion". However not every country complies.
"In many countries, including those in the former Soviet Union, it is still not recognised," said Mr Hetherington. "It has been a long, hard struggle but each year we hold the service in Tavistock Square there are younger people there. It is growing."
* ST MAXIMILIAN OF TEBESSA
More than 1,700 years ago Maximilian became the first conscientious objector when he was executed for his refusal to accept military service in the Roman army. The 21-year-oldrefused on the grounds that his Christian faith prohibited it.
* MUHAMMAD ALI
Cassius Marcellus Clay Jnr joined the Nation of Islam in 1964 and became Muhammad Ali. He refused to take up arms when he was drafted into the US Army in 1966 during the Vietnam War because of his religious beliefs. He was convicted and fined $10,000, stripped of his title by the professional boxing commission and banned from fighting in the US. His conviction was overturned.
* SIR MICHAEL TIPPETT
One of Britain's leading composers of the 20th century, Sir Michael Tippett was jailed for two months during the Second World War for his beliefs.
* BERTRAND RUSSELL
Bertrand Arthur William Russell, philosopher, logician, essayist and social critic, joined the No Conscription fellowship when the First World War started. In 1918 he was sentenced to six months in jail for a pacifistic article he had written. He was an anti-war and anti-nuclear protester until his death, aged 97 in 1970.
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