Disease was a very real problem for the troops here because water supplies and food were often contaminated and the casualty rate very high.
In March 1916 he transferred to New Zealand Field Artillery as a gunner and re-embarked for active service in France the following month.
In March he again transferred and was posted to 1st Battalion, Canterbury Infantry Regiment as a private, about the same time his brother Hector arrived in France.
Hector was wounded in one engagement and George, even though wounded himself, carried his brother for over a mile across 'no mans land' to safety. Due to the severity of his injuries Hector was invalided out.
Private George Marshall fought in the Ypres Salient, in the Passchendale area, at Poldehoeck Chateau and Crevecours.
After his return to France in 1917 he was involved in fighting the Germans near Crevecours.
Felicity's mother remembers her father describing vividly how a New Zealand soldier on his own, prevented the Germans from crossing a bridge and attacking a thin line of New Zealanders holding a ridge behind him. He held them off all day until reinforcements arrived.
"The Germans threw everything at him so there was at times dust all around the trench he was in. He pulled an old sack over his head so he was not visible.
After each barrage he would keep firing preventing anyone from crossing the bridge. When this occurred he could hear faintly the cheers of the soldiers lining the ridge behind him."
She suspects that this soldier was her father, in view of his description and what her Aunt Daisy (George's sister) wrote to their mother on May 27 1862: "I am very vague about it now.
He (George) was mentioned in dispatches, but I think he got the MM (Military Medal) when he was in charge of a Lewis machine gun. All his crew were either killed or wounded and he held the position until help came. I know that he did many brave feats, but he would never talk about it."
On one occasion when George was back from the front line he almost died of dysentery.
Private George Marshall was wounded in action in June 1917 in the opening phase of the Battle of Messines. After being evacuated to hospital in the UK, he rejoined his Battalion in the field in November.
He was promoted to Lance Corporal in April 1918 and Corporal in May.
In September he was awarded the Military Medal for acts of gallantry in the field and promoted to Lance Sergeant.
He returned to New Zealand in May 1919 and was discharged on June 6 1919.
In addition to his Military Medal he was awarded the 1914-15 Star, British War Medal and Victory Medal.
Corporal Marshall returned to New Zealand in 1919 and bought a farm at Cannington, South Canterbury and in 1926 married Felicity's grandmother.
The war took a terrible toll on his health and he spent much of his later years on a war pension.
Even so he was very involved training machine gunners with the Home Guard during the 1939-45 war.
Felicity's mother moved to the North many years ago and they have no family in the Canterbury district, only out on Banks Peninsula where her grandfather originally came from.
"My grandfather's medals really meant nothing to him back then because he lost many of his comrades in the war.
"He died of cancer 13 years before I was born at the age of 51, but his memory will always live on in my heart."