Dobbin was due to being his studies at Balliol College, Oxford in the autumn of 1914, but this was put on hold to enlist when war broke out.

He and his sister Charis opened their family's house in London as a meeting place for their friends as young men converged to join the war effort.

"On the 30th July he went back to Flanders for the last time. The rest is best told in the words of one of his fellow- officers. *He was bomb officer and was in his element, leading all the bomb counter-attacks successfully and never getting a scratch. He could throw extraordinarily well and he used to frighten the Germans by getting tonite bombs into their trenches 1 50 yards away. That night (August 15th) Barnett had to start a working party at a place where our trench touched the German trench, with only twenty yards of unoccupied trench in between. He was warned to be careful, as the Germans had a machine gun and several rifles trained on the spot, but with his usual courage he got up on the para- pet and from there directed the working-party. A flare showed him up and he was fired at immediately and one bullet hit him in the body.' The wound was clearly serious and he was carried from the trenches. On his way back, he met the officer who was to relieve him, and insisted on giving him some further directions about the work that he had meant to complete. He spoke a few words to his Colonel and to a brother-officer ; but his mind was already beginning to wander. After leaving the dressing station, he lost consciousness and died early on the morning of August i6th at Poperinghe, where he rests. ' It's a great ending ' he wrote of the death of a school-friend in action at the Dardanelles : the words were to come true of himself."
-from a published book of Dobbin's letters from the Front, which you can read in its entirety here: https://openlibrary.org/books/OL14003252M/Denis_Oliver_Barnett

"The news made its agonizing way home. On August 19th, his family received a War Office telegram saying that he had been wounded; that evening they received letters from the front informing them of his death. The next day, [Dobbin's] father wrote to the War Office asking for conformation... A month later, Percy Barnett again wrote to the War Office, on black-edged paper, to complain that Dobbin's glasses, regulation revolver and automatic pistol had been left out of the effects forwarded to his family. The grieving father explained that the items were wanted for a cousin headed for the front-but it is hard not to hear, also, the final outrage at the idea Dobbin was being robbed even as he lay dying far from home."
-Mo Moulton, 'Mutual Admiration Society'

"Dobbin met his cousin Sydney Frankenburg (who would later become his brother-in-law) while in France. "Dear old Sydney" took him to what both were surprised to discover was not a lace-making establishment, as advertised, but a brothel. "But we emerged with our good Semitic morals unsullied," Dobbin assured his sister, enclosing a piece of lace that she kept for the rest of her life."
-Mo Moulton, 'Mutual Admiration Society'