As a wartime artist, he popularised the concept of the Australian digger as independent, easy-going and disrespectful of authority, with a sardonic attitude to life.

Over his career Hartt produced a large number of cartoons on a broad range of subjects and themes; his drawings encompassed political, social and military topics and were admired for their observational humour and the quality of his character portraits.

He mainly drew single-panel cartoons, but his body of work also includes early examples of Australian comic strips.

[3] In about 1887, James Hartt took a job as a bookkeeper at Alfred Billson's Anglo-Australian Brewery at Beechworth, in north-east Victoria.

[11][12] During this period, Hartt began taking instruction in drawing from Alex Sass, an older artist who was working as a cartoonist for Melbourne Punch.

[16][15] Late in the morning on 3 June 1908, near Auburn railway station, James Hartt took his own life by placing his head on the rail as a train approached.

[12] In July 1909 he married Ruby Manners in the Newcastle suburb of Hamilton and a son, named Lawrence, was born to the couple in March 1910.

[27] In 1915, Hartt was part of a group called the Newspaper Cartoonists' Association of New South Wales which published Sydneyites: As we see ’em 1913-14-15, a book of "representative citizens" of Sydney (all men), each image combining a drawing with a photograph of the subject's head.

His next of kin was recorded as his wife Ruby, living on Pittwater Road in Dee Why, a northern beach suburb of Sydney.

Hartt enlisted at Liverpool in Sydney in March 1915, shortly after the outbreak of World War I and was placed in B Company of the 18th Battalion of the Australian Imperial Force.

[3][34] His drawings in Humorosities portrayed the Australian 'digger' as self-reliant, easy-going and disrespectful of authority, "more interested in avoiding tedious rules than in obedient conformity".

He invited Hartt to send "an original sketch or two... with the prices marked" with a view to their inclusion in "the King's collection of drawings".

[29] During the journey to Australia, Hartt and one of his comrades issued regular editions of a one-page news-sheet called The Bonzer Times.

After Reid returned to Australia from the Middle East in October 1918, he went to the Bulletin office "to collect a tidy cheque for scores of contributions" he had sent while on military service overseas.

Hartt was in the Bulletin office "making enquiries about the possibilities of working up an Australian edition of 'The Passing Show', a humorous London weekly, but somehow he didn't get much encouragement from the big newsagents, and the idea was dropped".

Smith engaged theatrical publicist Claude McKay and journalist Clyde Packer in the new venture, with J. F. Archibald of The Bulletin as consulting editor.

[24][41][42] Hartt's drawing style and humour were consistent with the populist left-wing ethos of Smith's Weekly, which set a radical nationalist tone and a disrespect of authority.

[47][48][49] From July 1919 until October 1924, Smith's Weekly featured a regular column called the "Sailors' and Soldiers' Parliament" that covered issues and stories specific to returned servicemen.

[54][55][B] One of the regular characters created by Hartt was 'Dummy', the hapless clown, described as "Australia's national figure of pathos" who "carries all the burdens and woes of our beloved country".

[57] The character was frequently used by Hartt to denote the "long suffering" Everyman, the "poor witless creature" who was "the butt of every politician and tax-gatherer, victim of every unscrupulous tradesman".

[56][58] Before very long, the concept of 'Dummy' took on a life of its own, being adopted as a recurring motif at Smith's Weekly by journalists, poets and other artists (alongside Hartt's own depictions of the character).

[59] At the inaugural Artists' Masquerade Ball held at Sydney Town Hall on 21 August 1922, Hartt attended the event dressed as his own 'Dummy' character.

[63] The original inspiration for 'Bill' was said to be Billy Bournes, a war-time Labor agitator and anti-conscriptionist who eventually went to live in Tennant Creek.

[68] The artist James R. Jackson entered a portrait of Cecil Hartt in the 1922 Archibald Prize competition at the Art Gallery of New South Wales.

[3][13] In March 1923, Hartt sued for divorce from his wife Ruby "on the grounds of adultery" with a man named William Wilson.

[73][74] In the following years, Hartt continued to be involved with the Society in various capacities, including on organising committees for the annual Black and White Artists' Ball.

[D] His body was found on 20 May near his abandoned motor car on the Pollwombra Mountain road, about three miles (4.8 km) north of Moruya.