[2] As a young man he obtained a farm managers position on Alex Mitchell's Surveyors Creek property near Woolbrook, high in the New England district of New South Wales, raising sheep.

Barwick embarked in the First Australian Imperial Force (AIF) sailing on the steamship HMAT A19 'Afric' on 18 October 1914[2] and stopped at Albany, Western Australia, from 25 to 31 Oct 1914 for a gathering of military ships.

During regular periods of leave they would usually go into Cairo, and explore the maze of souks (aka markets) and have wild parties in the cafes and bars.

They watched and were deafened in shock and awe, as the accompanying British Royal Navy battleships launched a preparatory bombardment down on Turk positions on Gallipoli.

There his 1st Battalion comrades Len Keysor was awarded the Victoria Cross for quickly throwing back unexploded Turk bombs on the 7 and 8 Aug, and Alfred Shout was awarded the Victoria Cross for charging down lost trenches throwing bombs at Turks on the 9 Aug. Barwick fought in the Action of Hill 60, Suvla on 21-27 Aug 1915[7] and remarkably survived 8 months of conflict.

Archie Barwick fought in an engagement near Demicourt, Artois, in the Hindenburg Line Campaign, and was wounded in action again, with a gunshot through his right shoulder on 8 Apr 1917.

He was admitted to the 6th General Hospital in Rouen, Normandy[2] and made a quick recovery and rejoined the 1st Battalion on 22 Apr 1917, as it was fighting up to the Hindenburg Line.

He fought in the Battle of Bullecourt II from 3–17 May 1917,[7] where his 1st Battalion comrade George Howell was awarded the Victoria Cross for running along a parapet of a lost trench throwing bombs down on Germans on the 6 May 1917.

Barwick obtained a position as an Instructor for the Australian 1st Training Battalion at Durrington Camp near Salisbury, Wiltshire, England.

[7] After a further 6 months conflict, he was wounded in action for a third occasion, when an exploding shell in the battle caused severe chest injuries on 15 Apr 1918.

He was discharged to leave in London but unfortunately caught the Spanish Flu and was admitted to Harefield Hospital, Wiltshire on 26 Jun 1918 for 3 weeks treatment.

After 6 months treatment and rehabilitation he obtained Special Leave for 1914 soldiers and went to St Budeux Barracks, Devenport on 16 Oct 1918.

[13] After training in England, Stan was sent to war and went to the 1st Australian Division Base Depot at Etaples, France on 11 Apr 1917, where he was reunited with his brother Archie recovering from his second wound, from 16 to 21 April 1917.

[23][24] About 4 oclock Reveille sounded & upon we all jumped & got dressed ... we heard a tremendous roar, up we all rushed, to get a look at what was going on, one of our ships had opened fire on "Gaba Tepe" soon the whole fleet of warships were belting away for all they were worth ... we watched this scene for about 10 minutes, & the order came for every man to get ready to move off ... about 5 or 5.30 we heard a crackle of rifle fire & we knew then that the 3rd Brig.

had landed, we then got the order to fill the boats & down we filed on to a destroyer ... she had a few wounded & dead men on her, they were the first we had ever seen, they made no difference to us, & now let me say right here, for it is true as true can be, those of our chaps who had cards, fetched them out & started playing ... the destroyer rushed us over as fast & as far as she could & then the sailors met us with rowing boats we quickly filled these & off we went with shells bursting all around us, we were lucky in our boat for only one man was hit ... we reached the beach at last & we leaped out quick & lively, I must have jumped into a deep place for I went in up to my arm-pits & had to struggle ashore with about 150 lb on my back, & rifle held high over my head to keep it from getting wet.

some of our Battn's boats were not so lucky as we were, for one or two of them got smashed right up & everyone was drowned they would sink like a stone with such a weight on them after we got ashore Lieut Payne got us together & we started up for the firing line.

... we scrambled up the hill for about 200 yards, & then we dumped our packs, & started off at a fair pace for the firing line ... it did seem funny to hear the bullets cutting into the scrub alongside of us as we went along, but no one seemed afraid, & we were laughing & joking as we went along, I don't want you to think I am skiting when you read this, for I will take my oath on it that it is true, I know myself I never felt the slightest fear the first day or two, it was when we began to realize that bullets hurt when they hit you, that we knew what fear was.

The couple had three children, John, Judy and Tim, and lived on the property Rooya, Abington Creek near Armidale, New South Wales.

When invasion by Japan was feared in World War II, Barwick was placed in charge of the local Volunteer Defence Corps.