Taking up a teaching post in Harrogate he continued to play amateur football and was approached by Bradford Park Avenue FC and asked to play for them as a professional.

He made his debut against Wolverhampton Wanderers (Wolves) on 13 April 1913 and went on to make five league appearances for Bradford before the outbreak of the war in August 1914.

Within weeks of war breaking out Bell sought to be released from his contract and joined the West Yorkshire Regiment, becoming the first professional footballer to enlist.

With his education and physical prowess Bell soon rose through the ranks and was commissioned as a 2nd Lieutenant into the 9th Battalion The Yorkshire Regiment (The Green Howards) in June 1915.

At the end of June 1916 the 9th Green Howards were in France to take part in the Battle of the Somme.

At 18:00 hours on 5 July 1916 the 8th and 9th Battalions of the Green Howards were ordered to capture Horseshoe Trench, which stood on high ground between La Boisselle and Mametz. As soon as they had left their trenches a German machine gun position began to enfilade the 9th Battalion causing serious casualties and halting the advance.

On his own initiative, Bell and two of his men made their way up one of the communication trenches toward the gun. Once they were as close as they could get Bell made a dash for it over the open ground, moving with speed and agility he surprised the machine gun crew. He shot the gunner with his revolver and blew up the remainder with his Mills bombs.

The citation for his Victoria Cross was published on 9th September 1916:

For most conspicuous bravery. During an attack a very heavy enfilade fire was opened on the attacking company by a hostile machine gun. 2nd Lt. Bell immediately, and on his own initiative, crept up a communication trench and then, followed by Cpl. Colwill and Pte Batey, rushed across the open under very heavy fire and attacked the machine gun, shooting the gunner with his revolver and destroying the gun and personnel with bombs.