Horace Collier was born in the Spring of 1890 in Hemel Hempstead, Hertfordshire, the sixth child and youngest son of Charles Collier and Eliza (Elizabeth) Walker, who had a large family of nine children together. The children were: Frederick, Walter, George, Eliza, Bertie, Horace, Rose, Daisy and Emma. Horace’s sister Daisy died in 1918, aged twenty-three and his father Charles a year later in 1919, aged sixty-one. His oldest brother Frederick, served with the Labour Corps during the war and was twice injured and admitted to hospital, once with a skull fracture incurred when a truck he was loading with 60lb shells overturned and trapped him. Despite these injuries, Fred survived the conflict.

After leaving school in 1903, Horace followed his older brother Bertie into Kent’s Brush Factory in Apsley and soon afterwards they were joined there by their sister Rose. On the 1911 Census, Horace was recorded as a "Box Maker" in a brush factory, but it was also noted that he and Bertie were both "out of work" at the time. The reasons for this note regarding unemployment are not known, nor whether Horace ever returned to work at G. B. Kent & Sons, but it seems he was not there when war broke out, as he was not recorded on the firm’s Memorial Plaque.

Horace enlisted in October 1915 under the Group (Derby) Scheme when he attested at Hertford and where he enlisted with the Hertfordshire Regiment. Following his basic training, Horace was sent to France to join his unit, 1/1st Battalion, and it is most likely that he arrived in April 1916 near Vielle Chapelle. Horace fought in the Battle of Ancre Heights in October and then in the Battle of Ancre in November, the final action of the costly five month long Somme Offensive. By the end of November, the 1/1st Herts had moved to Belgium and took up position on Canal Bank close to Ypres.

At the end of July 1917, The Battle of Ypres began with fighting at Pilckem Ridge which proved costly for the battalion, although Horace survived. In September, he fought at Menin Road and then Polygon Wood and it seems that it was there, or a month later following the Battle of Passchendaele, that Horace was gassed. The Battalion war diaries recorded that in September "6 ORs – gassed" and again on the 31st October "21, gassed".

Horace and the other wounded men were taken out of the line and he was invalided back to England to recover. The effects of gas poisoning could be fatal if large quantities were inhaled, but when gas attacks occurred warnings were sounded and, on most occasions, soldiers had time to don a gas mask. More often than not, a soldiers gas injuries related to severe blistering of the skin which would partly or completely heal during a period of between six and eight weeks. It seems this was the case for Horace as he was sent back to the Front in January 1918, but this time to a Base HQ to await a new posting. In February he was posted to his new unit the 6th Battalion Princess Charlotte of Wales’s (Royal Berkshire) Regiment which was almost immediately disbanded. He was then posted to the 2/4th Battalion of the Regiment. Horace joined his new Battalion on the 21st February 1918 along with “…2 Officers and 235 Other Ranks…” as noted in the unit’s war diary.

In late May the 2/4th Royal Berks were in the vicinity of Saint-Venant and over a number of days, its position came under artillery attack from the enemy which resulted in twenty-three men killed or wounded. Horace was one of the unfortunate soldiers to receive wounds and he was admitted to hospital on the morning of the 30th May in a dire condition. Efforts to save him were to no avail and it is clear from reports that his wounds were extensive and fatal.

Horace died in hospital of his wounds at 11pm on Thursday, 30th May 1918. Horace was interred in a short service conducted by the Battalion Chaplain, Revd. Ellis Williams, on the 1st June.

His mother received two letters in early June describing the circumstances of his death as well as the location of his burial and both were published in the Hemel Gazette shortly afterwards. The letters were written by the Chaplian who buried Horace and the "Sister-in-Charge" in the hospital wher he died, one B. J. D. Reid.

Horace is Remembered with Honour in Aire Communal Cemetery, Pas-de-Calais, France, where he is interred in Grave II. K. 45.The inscription on his headstone, requested by his mother Eliza, reads: “GONE FROM US BUT NOT FORGOTTEN”

He was 30 years old when he died.

Horace was eligible for the British War Medal and the Allied Victory Medal.