The May 1916 extension of the Military Service Act

The Military Service Act of 27 January 1916 brought conscription into play for the first time in the war. Along with the Defence of the Realm Act, it was possibly the most important piece of legislation in placing Britain onto a "total war" footing. It was extended and new conditions implemented in legislation of 25 May 1916, which was known as the Military Service Act, 1916 (Session 2). Together they were known as the Military Service Acts, 1916.

The definition of who was in scope for conscription was changed to include all men who had been at any time resident in Great Britain since 4 August 1914 who had attained the age of 18 but was not yet 41 unless he was in the exceptions defined in the Schedule attached to the first Act. In other words, it added married men to the scope of conscription and reduced the minimum age to 18.

Paragraph Five of the Schedule of exceptions (that is, "Men who had served with the military or Navy and been discharged on grounds of ill-health or termination of service") ceased. Men who had been discharged became eligible for service again. If he was a Warrant Officer or NCO when previously discharged, he was restored to this rank while in reserve and awaiting call-up.

Paragraph Six of the Schedule of exceptions (that is, "Men who have offered themselves for enlistment since 4 August 1914 but been rejected";) ceased on 1 September 1916.

The new Act made clear than no man who had at any time been a Prisoner of War (or captured or interned) would be liable for service.

It also made made provisions that, contrary to the Territorial and Reserve Forces Act of 1907, that a man serving in a Territorial corps could without his consent be transferred to another corps or to the regular army or to any unit within the same corps. The latter was also made applicable to Territorial officers. The man's rate of pay would not be affected by any such transfer.