At the outbreak of war with Germany in 1914, the 4th Hussars was mobilised as part of the British Expeditionary Force (BEF) making its way to Dublin for embarkation to France. The regiment travelled with its horses aboard the SS "Atlantian", arriving in Le Havre on 15 August 1914. The 4th Hussars formed part of the 3rd Cavalry Brigade commanded by Brigadier General Hubert Gough, and quickly became embroiled in the Battle and subsequent Retreat from Mons. During these actions the commanding officer, Lieutenant Colonel Ian Hogg, died from wounds received in a rearguard action on 1 September. Howell assumed command of the 4th Hussars through the Battle of Le Cateau, until relieved by the appointment of Lieutenant Colonel Tom Bridges on 27 September. However, Bridges appointment lasted three days, before he was promoted brigadier general and sent to become chief military adviser to the King of Belgium. Howell resumed command of the 4th Hussars, being promoted lieutenant colonel on 18 October. He led the 4th Hussars throughout the remainder of the advance of First Battle of Marne, and then in the following ten months through the frontline carnage of the First Battle of Ypres, Hill 60, and Neuve Chappelle.