The best known humanitarian roles of Switzerland relates to prisoners of war (PoWs). By the end of 1915, after a year and a half of war, there were already some 2.5 million prisoners held by the two warring sides. The main source of Swiss aid was through the Red Cross. It was founded by the Swiss Henri Dunant in the 1860s, comprising an international committee based in Geneva (The International Committee of the Red Cross or ICRC) and separate but affiliated national Red Cross organisations. .

National Red Cross organisations tended, amongst other tasks, to look after the well-being of PoWs of their own nationality who were held in enemy camps. The ICRC did not have such affiliations, and played a more general role. Two of the ICRC important roles were co-ordinating information about individual prisoners, and monitoring conditions in PoW camps. 

The ICRC was based in the Musée Rath in Geneva.The task of trying to keep track of individual PoWs was immense. By September 1914, the ICRC was already receiving 3,000 letters per day, each enquiring about a person who was thought to be held prisoner. Every letter was replied to individually, and in the first year of war nearly 235,000 letters were sent out.

The ICRC began recording information about individual prisoners of war and civilian internees on a card index, which by the end of the war the index covered some seven million names. The huge correspondence was handled by volunteers.  About 120,000 people visited the ICRC in person to try to trace relatives.   

As well as the ICRC at Geneva, there were other organisations in Switzerland attempting to trace missing PoWs or civilians, as well as to send aid to PoWs. The Swiss Red Cross in Berne sent aid parcels to PoWs. Individuals or regimental organisations in the prisoner's own country could request that the Swiss Red Cross send aid to a particular PoW. Some of the most common items sent were bread, chocolate and Nestlé’s milk (condensed milk). The flour for the bread sent to PoWs was actually imported from France, which illustrates Switzerland’s dependence on imports. 

In late 1916, the Swiss Red Cross were sending out about 25,000 bread parcels each week as so little food was available in Germany. In April 1916, Lt. William Reid RFC, a prisoner of war in Germany, wrote home to his parents “You ask about the bread from Switzerland. Well, it takes about two weeks to arrive, so it is rather stale by the time it gets here. It is also remarkably full of holes, but it’s quite eatable”.

Between mid-October 1914 and the end of June 1916, the ICRC’s agency for the care of PoWs had sent over 30,400,000 parcels. Letters, postcards and parcels were forwarded to PoWs by the Swiss post office: In March 1917 for example, over 420,000 letters and postcards, and 80,000 parcels were sent.

The International Committee of the Red Cross (ICRC), based in Switzerland, monitored conditions in prisoner of war (PoW) camps in the warring countries. These camps were inspected to ensure that both sides were meeting agreed international conditions for the care of PoWs. Using at most only forty-one delegates at any one time, the ICRC visited 524 camps in Western and Eastern Europe, North Africa, Russia and Japan.  Food, hygiene and the state of the prisoners' quarters were the main focuses of attention during these visits.

The ICRC's reports on visits to individual camps were published, sharing the information with the general public and enabling the ICRC to put pressure on any nation which did not meet the standards.  

At the suggestion of the International Committee of the Red Cross (ICRC) and the Swiss government, Germany, France, Britain, Russia and Belgium signed an agreement in 1914 regarding prisoners of war (PoWs). The agreement stated that captured military and naval personnel who were too seriously wounded or sick to be able to continue in military service could be repatriated through Switzerland, with the assistance of the Swiss Red Cross.

The first repatriations were made in March 1915 and by November 1916 some 8,700 French and 2,300 German soldiers had been repatriated. POWs arriving

The next step was the internment in Switzerland of PoWs who, though sick or badly wounded, might still be capable of military work away from the front line, and could therefore make fit soldiers available for serving at the frontline, if they were repatriated. Internment in Switzerland would aid their recovery without furthering the enemy’s war effort. At the suggestion of the ICRC, a reciprocal agreement was signed between Germany and France. The UK and Belgium signed agreements with Germany slightly later. Travelling commissions of Swiss doctors visited PoW camps to select potential internees. Once a PoW had been selected, he would be brought before a board comprising two Swiss Army doctors, two doctors from the country holding him captive, and a representative from the prisoner’s own country.

The first of these internees, 100 German and 100 French PoWs suffering from tuberculosis, arrived in Switzerland in January 1916. By the end of 1916, nearly 27,000 former PoWs were interned there, about half of whom were French, one third German and the remainder mostly British or Belgian. As the internees entered Switzerland and at stages along their journeys, they were often surprised to be greeted by thousands of Swiss who had turned out to welcome them.  (Photo above right: PoWs arriving)

By the end of the war, nearly 68,000 men had been brought to Switzerland for internment. Selection for internment was done on the basis of individual needs, rather than on a quota or exchange basis by nationality. Some civilians were also interned, presumably men who were of military age who had been detained in enemy countries. 

Internees were held or worked at a number of locations. For the British, the main camps were in south-western Switzerland, east of Lake Geneva. One of the main centres for interned British was in the vicinity of Châteux d’OEx. The first interned British ex-PoWs to reach Switzerland, about 300 officers and other ranks, arrived there on 31 May 1916. Some 700 British internees were eventually held in the vicinity. Leysin was used for British tuberculosis sufferers.   

Another camp for British internees was at Mürren, which held 600 men and 30-40 officers. This village was built on a ledge high up a mountain, and for seven months each year was virtually cut off due to snow. Although the view was beautiful, many of the internees were so badly ill or wounded that they were confined to their billets when it snowed. 

Life for the internees was not necessarily easy. They were still under military discipline, enforced by the Swiss commandant of their camp. Regular roll calls were held, and if a man was found to be missing without permission, for example, he might be briefly imprisoned on his return. Some German internees were said to have preferred the English PoW camps to the Swiss. Items made by internees were sometimes sold to raise money to contribute towards their care

A small number of Austro-Hungarians were also interned, but apparently no Russians. No Americans were interned, because the US and Germany only signed an agreement on this issue on 11 November 1918.

A British report compiled in late 1917 found that some camps were not in places suitable for wounded men to recover, that there were insufficient medical staff, and that artificial limbs were not available for men who needed them. Boredom often added to existing psychological effects of having been a prisoner of war for several years.

If their wounds or illness permitted, interned other ranks were expected to work, such as on farms. Depending on the long-term effects of wounds or illness, this work could range from working for a private Swiss firm in the internee’s pre-war profession, to learning a new trade which would be useful after the war, if the internee could no longer follow his old one.

The terms under which internment occurred changed over the course of the war, as individual countries made bilateral agreements. Under a May 1917 agreement between France and Germany, internees were automatically repatriated to their home country after being in captivity for more than eighteen months, if over a specified age. An Anglo-German agreement in mid-1917 broadened the terms of eligibility for internment to men who had spent at least 18 months in captivity and who were recognised as suffering from so-called “barbed wire disease”, meaning the mental strain of being held prisoner.

It was also agreed at this time that internees whose recovery was likely to be prolonged would be repatriated. One internee who was repatriated in 1917 due to wounds suffered was Arthur Whitten Brown, who made the first trans-Atlantic crossing by air in 1919. Although in theory repatriated ex-PoWs were meant to be no longer fit for military service, he seems to have served as a flying instructor. 

Not all internees left Switzerland at the end of the war. By 1923, a British war cemetery had been constructed at Vevey, on the north-east shore of Lake Geneva. This holds 88 British graves, mostly those of internees who had succumbed to their wounds or had died in the influenza epidemic. These were the most frequent ways that troops of the belligerent states came to be interned in Switzerland. However, there was another way. Any soldiers who crossed the frontier into Switzerland, whether deliberately or accidentally, would be disarmed and interned. One example was the crews of a number of aircraft that landed (or crash-landed) in Switzerland.

Swiss humanitarian work involved civilians as well as military personnel. In 1914-1915, over 20,000 French, German, Austrian and Hungarian nationals who had been detained in enemy states on the outbreak of war were repatriated through Switzerland on an exchange basis. In addition in August 1914, some 100,000 Italians who had been living in belligerent countries returned to Italy (which was not yet at war) through Switzerland, assisted by the Swiss Red Cross.