Inglis served in the Royal Engineers during the First World War and invented the Inglis Bridge, a reusable steel bridging system – the precursor to the more famous Bailey bridge of the Second World War. In 1916 he was placed in charge of bridge design and supply at the War Office and, with Giffard Le Quesne Martel, pioneered the use of temporary bridges with tanks. Inglis retired from military service in 1919 and was appointed an Officer of the Order of the British Empire.