Simpson was a kind man who loved animals. He had only been on Gallipoli one day when he found a donkey.
The donkey was alone nibbling grass near a soldier needing help.
When Simpson was a boy growing up in England he used to give children donkey rides on the beach.
"I’ve got an idea," said Simpson. Pulling a handful of bandages from his pocket he made a halter for the donkey.
Then, carefully, he lifted the soldier onto the donkey’s back.
Guiding the donkey and holding on to the man, Simpson set off for the dressing station.
The Australian soldiers looked on in amazement.
"There goes Simpson," they said.
"Not with a stretcher, not with a man across his shoulders, but with a man on a donkey!"
Simpson called his donkey Duffy.
Many times a day, and sometimes into the night, Simpson and his donkey went up the dangerous Shrapnel Gully to bring back soldiers wounded in the fighting.
When they reached the battlefield, Simpson tied Duffy to a tree out of sight.
Then he waited, crouching in the bushes until it was safe to run forward and drag a man to safety.
After bandaging the wounds, he lifted the soldier onto Duffy’s back.