The Visitation Committee of the United Synagogue were responsible for the religious welfare and spiritual needs of Jews in public bodies and it decided to include serving members of the British Forces in its remit and applied to the War Office for the appointment of a Jewish chaplain.

[10] Adler became a commissioned chaplain with the rank of captain in the Territorial Force (London and Eastern Command),[11] attending summer camps on Salisbury Plain where he conducted services for Jewish soldiers.

At first the duties of the Jewish chaplains were part-time and included an annual Hanukkah military service initiated by Rabbi Cohen.

In the first month of the War Adler wrote a Soldiers’ Prayer Book which Chief Rabbi Joseph Hertz (who visited France in June 1915) later enlarged.

Adler requested the War Office that he be allowed to visit to the Western Front to assess the need of a Jewish chaplain there, which he did in January 1915.

After he wrote a report for the War Office he was granted permission to serve on the Western Front, where initially he was the only Jewish chaplain.

[1] The Chaplain General, John Taylor Smith (1860-1938), suggested that instead of the usual Christian chaplain's badge, the Rev Adler should wear a Magen David to make him easier to identify,[9] and soon after arriving at the Front Adler arranged for Jewish military graves to be similarly marked with a Magen David rather than the traditional Cross.

In July 1918 his health broke and he returned to the UK with the rank of major, commenting to a colleague that after he left the Front the Allies succeeded.

[2][14][15] Adler undertook the monumental task of recording the names and units of the approximately 50,000 British Jewish soldiers and sailors of the Empire and Dominions who had served, been killed or been decorated during World War I.

Rabbi Michael Adler died in a nursing home in Bournemouth in 1944 aged 76 and was buried in Willesden Jewish Cemetery.