[3][13] In July 1913, after enduring a period on half-pay,[14] he succeeded Brigadier General Edward Bulfin in command of the Essex Brigade, part of the East Anglian Division.
[15] Shortly after the British entry into World War I, in August 1914, Lawford was promoted to the temporary rank of brigadier general that same month[16] and commanded the 22nd Infantry Brigade, part of the newly organised 7th Division, during all of its engagements on the Western Front from 1914–1915, during which time he was made a Companion of the Order of the Bath in February 1915.
This was the most junior division of Lord Kitchener's New Armies, and Lawford would remain as its GOC from 1915 to 1919, which included brief service on the Italian front from December 1917 until March 1918.
[20] His military nickname was 'Swanky Syd', apparently derived from his habit of donning full dress regalia, including all of his medal entitlement, regularly.
[28] While serving in India in the early 1920s, and while still married to Muriel, he fell in love with the wife of one of his officers, May Somerville Aylen (4 November 1883 – 23 January 1972), and she became pregnant with his child.