It is generally assumed that during WWII chaplains were unarmed. Crosby describes an incident where a US chaplain became a trained tank gunner and was removed from the military for this "entirely illegal, not to mention imprudent" action (1994, pxxi). At least some UK WWII chaplains serving in the Far East, however, were armed: George MacDonald Fraser recalls (1995, p109) "the tall figure of the battalion chaplain, swinging along good style with his .38 on his hip" immediately behind the lead platoon during a battalion attack. Fraser asks "if the padre shot [an enemy], what would the harvest be ... apart from three ringing cheers from the whole battalion?" (1995, p110).
In recent years both the UK and US have required chaplains, but not medical personnel, to be unarmed. Other nations, notably Norway, Denmark and Sweden, make it an issue of individual conscience. There are anecdotal accounts that even US and UK chaplains have at least occasionally unofficially borne weapons: Chaplain (then Captain) James D. Johnson, of the 9th Infantry Division, Mobile Riverine Force in Vietnam describes (Combat Chaplain: A Thirty-Year Vietnam Battle) carrying the M-16 rifle while embedded with a combat patrol. Since 1909 US Chaplains on operations have been accompanied by an armed 'Chaplain (sic) Assistant'.
, however perhaps on this occasion it was felt that an unarmed uniformed man would draw unwelcome attention.
Captured chaplains are not considered Prisoners of War (Third Convention, 12 August 1949, Chapter IV Art 33) and must be returned to their home nation unless retained to minister to prisoners of war.
Inevitably, serving chaplains have died in action, sometimes in significant numbers. The U.S. Army and Marines lost 100 chaplains killed in action during WWII: a casualty rate greater "than any other branch of the services except the infantry and the Army Air Corps" (Crosby, 1994, pxxiii). Many have been decorated for bravery in action (five have won Britain's highest award for gallantry, the Victoria Cross). The Chaplain's Medal for Heroism is a special U.S. military decoration given to military chaplains who have been killed in the line of duty, although it has to date only been awarded to the famous Four Chaplains, all of whom died in the USAT Dorchester sinking in 1943 after giving up their lifejackets to others.
Military Chaplains are normally accorded officer status, although Sierra Leone had a Naval Lance Corporal chaplain in 2001. In most navies, their badges and insignia do not differentiate their levels of responsibility and status. By contrast, in Air Forces and Armies, they typically carry ranks and are differentiated by crosses or other equivalent religious insignia. However, United States military chaplains in every branch carry both rank and Chaplain Corps insignia.
Chaplain's badges and insignia follow this general pattern (taken from the Royal Australian Navy):
The current form of military chaplain dates from the era of the First World War. A chaplain provides spiritual and pastoral support for service personnel, including the conduct of religious services at sea or in the field. In the Royal Navy chaplains are traditionally addressed by their Christian name, or with one of many nick-names (Bish; Sin-Bosun; Devil Dodger; Sky-Pilot; God Botherer etc). In the British Army and Royal Air Force, chaplains are traditionally referred to (and addressed) as padre.
In the Royal Navy chaplains have no rank other than "chaplain" while in the British Army they hold commissioned executive rank. On the foundation of the Royal Air Force Chaplains' Branch an attempt was made to amalgamate these differing systems creating "Relative Rank", where rank is worn but without executive authority. In practice chaplains of all three services work in similar ways using what influence and authority they have on behalf of those who consult them or seek their advice.
During World War II the head of Chaplaincy in the British Army was an (Anglican) Chaplain-General, (a Major-General), who was formally under the control of the Permanent Under-Secretary of State. An Assistant Chaplain-General was a Chaplain 1st class (full Colonel) and a senior Chaplain was a Chaplain 2nd class (Lieutenant Colonel).
All chaplains are commissioned officers and wear uniform. British Army and Royal Air Force chaplains bear ranks and wear rank insignia, but Royal Navy chaplains do not, wearing a cross and the officers' cap badge as their only insignia.
Chaplains in the armed forces were previously all Christian or Jewish. In recent times, the Ministry of Defence (MoD) has employed only Christian chaplains, with the Jewish community providing an honorary chaplain under longstanding arrangements, although Jewish chaplains have served in the Territorial Army. However, at the end of 2004, Ivor Caplin, the then Parliamentary Under Secretary of State at the Ministry of Defence announced that the armed forces would recruit four non-Christian chaplains, from Buddhist, Hindu, Muslim and Sikh communities, with a Jewish chaplain expected to be employed by the MoD in due course.
In the era before callsigns the radio "appointment title" for the Padre was "Sky pilot".
In the United States, military chaplains have rank based on years of service and promotion selection. They are identified in uniform of both rank and religious symbol insignias.
In the United States military, chaplains must be endorsed by their religious affiliation in order to serve on active duty. This religious endorsement must be obtained throughout the active duty years of service and in fact it can be withdrawn at any time by the religious body with which the chaplain is affiliated. Without such endorsement, the chaplain can no longer serve on active duty as a chaplain.
In January 1991 Lieutenant Colonel Garland Robertson, a US Air Force chaplain during Operation Desert Shield, wrote to the Abilene Reporter-News asserting that "... the American people are not united in their decision to support a military offensive against the aggression of Saddam Hussein in Kuwait."
Robertson was investigated by Air Force psychologists and relieved of his pastoral duties. According to Robertson, a visiting officer from the Chief of Chaplains office "indicated that compromise was essential for becoming a successful military chaplain," and that "if Jesus had been an Air Force chaplain ... he would have been court-martialled." 
US Navy Chaplain Lieutenant Gordon Klingenschmitt was reprimanded and fined
during a September 14, 2006 court martial for wearing his uniform at a protest in March 2006 held by Roy Moore. Klingenschmitt was released from the Navy in March 2007. He had been battling military policies that he considered to be an infringement of the rights of every chaplain to "conduct public worship according to the manner and forms of the church of which he is a member."
"Well, at the risk of being callous...I don't think that we should be paying for Chaplains...I don't think that the U.S. Government should be employing any. James Madison, co-author of the Virginia Statute for Religious Freedom and of the First Amendment was very adamant on the point, and very clear; there shouldn't be...it's flat-out unconstitutional to pay or to employ a Chaplain to oversee the proceedings of Congress or to be in the Armed Forces. We can't have Chaplains on our payroll, that's that.
Mr. Hitchens is not the first person to challenge military chaplains. This issue has been the subject of extensive litigation in the past, most notably in 1986 with Katcoff vs. Marsh. The suit was brought in 1979 by two Harvard law students (neither of whom had served in the military) who argued that military chaplains should be replaced with civilian volunteers or contractors. In Katcoff v. Marsh the courts upheld the right of the military to employ chaplains. This case is the subject of a University of Toledo Law Review article (Vol. 38) by Richard D. Rosen. (The full text of the review article is here: http://www.usafa.edu/isme/ISME07/Rosen07.html) One key idea, as stated by Rosen, is "if Congress did not establish an Army chaplaincy, it would deny soldiers the right to exercise their religion freely, particularly given the mobile and deployable nature of the nation’s armed forces." Any civilian religious group that were presented with the cost of keeping a minister in the field, prepared to deploy with an army unit at a moment's notice, and provide for their physical safety and security in modern combat, plus transportation costs, would almost certainly balk at the cost. At best, this would mean only the largest, and wealthiest churches, could send ministers. Another key idea is that the "free expression" clause and the "establishment" clause of the first amendment regarding religion are separate issues. If civilian churches were required to field their own chaplains it would, as Rosen and the court decided, mean denying the soldiers "free expression" of their faith, and, in effect, deny soldiers access to, or opportunity, to practice their faith and infringing on their religious freedoms. The "free exercise" clause has largely become the primary reason chaplains exist. "[T]he Supreme Court has seemingly given the Free Exercise Clause – upon which the military chaplaincy is now largely justified – a preferred position in our constitutional order" (Rosen 1144-1145). The following is a rather extensive quote taken from Rosen's conclusion to the law review article it neatly summarizes the current legal and constitutional environment in which chaplains work(p. 1178):
"Ultimately, the price of maintaining a military chaplaincy is strict and abiding adherence to the dictates of the Establishment Clause; specifically:
●Military officials must fully accommodate the rights of service members to believe or not to believe in any particular religious doctrine (or even a Deity).
●Military officials must ensure that service members are neither punished for their beliefs nor subjected to unwanted proselytizing or evangelizing from military chaplains or senior officers and noncommissioned officers, even if the proselytizing or evangelizing is intended as a good-faith effort to salvage the spiritual health of the service members.
●Military officials may not subject members of the armed forces to involuntary worship or prayers, particularly when the full power of the government backed by punitive action under the UCMJ* is employed to command their presence and participation.
●Except when good order and military discipline are threatened, military officials may not discriminate against any particular religious sect or denomination, especially based upon the belief system of the sect or denomination.
While confirming the constitutional foundation for the existence of the military chaplaincy, the Katcoff decision neither immunized the armed forces from Establishment Clause scrutiny nor did it give the military leadership a blank check to administer the chaplaincy or religious practices in the armed forces without regard to the Establishment Clause. Military officials must always endeavor to ensure that they do not squander public and judicial support for the chaplaincy program by ignoring the constitutional boundaries governing the program’s administration and operations." (Rosen 1178)

Saint Louis was the king who gave legal status to the military almoners, since chaplains supporting their lord into crusades were the first to be militarized. In 1531, during the Battle of Cappel, the Swiss reformist, Huldrych Zwingli, became the very first Protestant military almoner to be killed in a battlefield.
The actual French Aumônerie Militaire (military almonry) status is based on the July 8th, 1880 law, which involves the Catholic, Protestant and Jewish faiths. The 1905 laicity law, definitely rejecting religion out of the French Republic, exceptionally, doesn't apply to the army. The Minister of Defence names three Chief-Staff-linked military almoners - one per faith - in charge of all chaplains. The civilian chaplains, serving in the army, are named by one of these three military almoners. The first Muslim Chaplain-General, Abdelkader Arbi, was commissioned in 2006. 1
French military chaplains wear a uniform, since World War II, but don't have any rank nor rank insignia. The modern military almonry is rooted in WWII, where military chaplains were incorporated in almost every Free French Forces fighting units and made of personnel coming from either Metropolitan France, England or from the French Empire. After the war, military almoners where sent to occupation zones in Germany and Austria.
In the 1950's, military almoners where sent in the French Union's territories, including Indochina and Algeria. In 1954, pastor Tissot was one of the last paratrooper volunteers to jump over the besieged Dien Bien Phu fortified camp in northern Vietnam. In May 7th, he was made prisoner of the Viet Minh and sent to a re-education camp, deep in the jungle.
Since 1984, French military chaplains are involved in every military operations - including the Gulf War - from Rapid Reaction Force (Force d'Action Rapide) units to navy ships.
Prior to 1968, chaplains wore badges of rank as commissioned officers.
Since 1968, however, all Chaplains have been senior officers and accorded the protocol status of Colonel / Captain (Navy). They carry the military rank of Chaplain and the rank insignia, which is unique to the Chaplains Service, comprises a Chi-Rho monogramme
surrounded by a triangle. The monogramme represents the first three letters of Christ in Greek. It originates from the days of Constantine, the first Emperor of Rome to grant religious freedom to Christians. His own conversion to the Christian faith was initiated by a dream in which the Chi-Rho monogramme appeared to him. The triangle surrounding the monogramme is the symbolic representation of the Holy Trinity.
During the vision of the monogramme, Constantine heard the words In hoc signo vinci. The English translation of these Latin words means, In this sign conquer. This is the motto of the Chaplains Service and forms part of the Corps Badge.
The Hindu faith is represented by a Regular Force chaplain. The rank is Cpln (Vipra) and the mode of address Vipra. The rank insignia is a deepa (lamp) with flame. This is the symbolic representation of enlightenment, the life objective of all Hindus.
The Muslims do not have Regular Force chaplains in the SANDF because of they are small in number. They are however served by part time workers through the Chaplains Service of the SANDF and are addressed according to their religious customs as imams.
Christian chaplains are generally referred to and addressed as Padre. They may however, be addressed according to the practice of their religious bodies eg, Father, Pastor, Umfundisi (Zulu and Xhosa), Moruti (Sotho), Dominee (Afrikaans) etc. The official written form of address is Cpln (for Chaplain) followed by the appropriate ecclesiastical title of the respective chaplain eg, Cpln (Rev), Cpln (Fr), Cpln (Pastor), Cpln, etc.