When confederate army Lieutenant Debney Scales was writing his diary aboard the CSS Shenandoah during the American Civil war, he could barely have imagined that more than 150 years later his words would be sought after on the other side of the world.

Lieutenant Scales' diary documents the Shenandoah's activities in the southern hemisphere during 1864 and 1865, in particular the weeks it spent in Melbourne as it was being repaired and restocked.

"This diary is remarkable," Melbourne historian Dr Angus Curry said.

Because of a shortage of paper at the time, Lieutenant Scales' diary is in fact written within the logbook of one of the 38 vessels attacked by the Shenandoah.

There are also many passages written in French.

"It really fills out the story and the narrative of the CSS Shenandoah from the people who were on board," Dr Curry told the ABC.

The State Library of Victoria is looking for public support to purchase the diary, which appeared in a recent auction in Tennessee, the US state where Lieutenant Scales was born.

"The Shenandoah appeared out of the blue one morning and was quite a shock to the citizens to realise that the civil war had come to their port, to their town," said Dr Kevin Molloy.

He heads the library's manuscripts department.

"It was the first and only time Australia had direct contact with the events of the civil war."

The Shenandoah was one of the most successful raiders during the war sinking 38 vessels. ( Supplied: State Library of Victoria )

Visitors 'blown away' by Melbourne reception

The CSS Shenandoah ship arrived on January 25, 1865. The following day Melburnians clamoured to be invited aboard.

"The officers were just amazed by the size and scale of the city and beautiful architecture, the streets and the welcome that was certainly something they didn't quite expect," Dr Curry said.

"They were completely blown away when they came to Melbourne and saw the public response to their visit."

During their three-week stay, officers were invited to many events, including a gala ball in Ballarat.

There were Americans living in Victoria at the time - drawn here by the goldrush - and they were divided just as their nation was.

The colonial government of the time was acutely aware of the divisions.

"The government of the time was terribly involved in the rights and wrongs of the Shenandoah being in the port - it was debated in Parliament," Mr Molloy said.

"The American consul at the time was very involved in trying to persuade the government to impound the ship because it was conducting illegal practices in the Pacific."

Stowaways needed for labour

When the ship departed on February 18, there were a few unexpected inhabitants.

"The pilot had no sooner left the ship, than stowaways began to make their appearance... 40 blushing, timid, unassuming-looking fellows stepped up to the grog tub," Lt Scales wrote

"They were stowaways in a very loose sense," Dr Curry said.

"The officers didn't want to acknowledge their existence but they desperately wanted the labour."

Much of the diary reflected the day-to-day running of the ship, with entries of longitudes and latitudes and the mundane tasks undertaken by the crew.

But Lieutenant Scales, who was in his 20s at the time, also revealed some personal moments.

"This is a young man, at sea, at war, quite aware of the rules of war, the rules of engagement and his diary has many very touching moments," said Dr Molloy.

"When they were up in the Bering Straits, his birthday was celebrated and he notes that this is the first time that anybody's celebrated his birthday."

The Shenandoah was a highly successful raider ship for the Confederates and continued to attack union vessels for months after the cessation of hostilities between the American North and South, mostly because the crew did not believe it when it was told the war was over.

It has the distinction of firing the last shot in the conflict.

It surrendered in Liverpool, England — the unofficial home to the confederate overseas fleet.