Complex sentence: On 1 April 1918, the Royal Air Force was created by the merger of the Royal Naval Air Service and the Royal Flying Corps, and accordingly Weston was transferred to it with the rank of lieutenant.
Split into simpler sentences: On 1 April 1918, the Royal Air Force was created by the merger of the Royal Naval Air Service and the Royal Flying Corps. Accordingly Weston was transferred to it, with the rank of lieutenant.