The name was a propaganda label, contrived to convey derogatory connotations and, most of all, utter disdain for their desperate rear-guard defensive action.
But the perverse Aussie sense of humour Europeans found difficult to understand, which so often came to the fore in stressful situations during World War II, won out.
The Rats of Tobruk adopted with pride the sobriquet (nick name) conferred on them by New York-born, Ireland-raised and England-educated fascist William Joyce - better known to Allied troops as Lord Haw Haw - during his Germany Calling propaganda radio broadcasts out of Hamburg.
The label became The Rats' badge of honour.
An unwitting acknowledgement by the enemy of their courage under fire, their resilience under intolerable conditions and an unwavering determination to hold on - which they did.
The Rats' legendary defence of Tobruk during a 241-day siege, started 80 years ago this month.
Military strategists still debate the tactical importance of keeping the small Mediterranean port with limited tonnage capacity, out of enemy hands during the second of three phases of the 1940-43 Western Desert Campaign in North Africa.
At stake was control of the Suez Canal to the east in Egypt, a vital lifeline for Britain.
Without Allied control of the canal Britain-bound oil tankers from the Middle East, would have to take the long way around the Horn of Africa and risk being picked off in the Atlantic by U-boat 'wolf packs' which decimated supply convoys from Canada and the United States of America.
Put very simply, in the first phase of the Western Desert Campaign Allied troops, in a pre-emptive strike from Egypt to protect the canal, captured a long coastal strip of neighbouring Libya from demoralised Italian forces.
In the second phase, British and Australian forces were chased out of Libya back into Egypt in a counter offensive spearheaded by Germany's Afrika Korps.
The Afrika Korps were equipped with Panzer tanks - seemingly unstoppable in their blitzkrieg across Europe in late 1939 and early 1940 - and ably led by Lieutenant-General (later Field Marshal) Erwin Rommel.
Rommel was dubbed the 'Desert Fox' in grudging recognition of his battle skills, while Australian troops contemptuously referred to their own hasty and sometimes chaotic retreat as the 'The Benghazi Handicap'.
Along the way, a small garrison force of mainly Australian troops - some of whom had not been in battle before - was left behind in early April 1941 to defend Tobruk.
The Allies' aim was to stretch to breaking point Rommel's supply line from Tripoli by denying him access to Tobruk's port, some 1000 kilometres closer to the rapidly-moving front line.
After failed attempts to wrest Tobruk from the garrison force in what became known as the Easter Battle in April and the Battle of the Salient in late April into May of 1941, Rommel pushed on a further 800 kilometres east into Egypt.
Only then did his stretched supply line - a single asphalt road across northern Libya - and reinforced Allied troops eventually stop his charge 380 kilometres short of its Suez Canal objective at a lonely Egyptian desert railway siding called El Alamein.
While the tactical importance of Tobruk is questioned, the bravery of and the hardships faced by those defending it during the siege, is never in doubt.
Australian Major-General Leslie Morshead (later promoted to Lieutenant-General and knighted for his efforts) was ordered to hold Tobruk for eight weeks.
He and his troops held out against an attacking force double their number and with greater firepower, for close on eight months.
Scorched in open trenches by the desert heat during the day and chilled by the winds at night, they were only able to be relieved in number when Allied troops reached them in November, ahead of the decisive final phase of the Western Desert Campaign the following year.
As chief Rat, Morshead led a garrison force consisting of the 20th, 24th and 26th Brigades of the Australian 9th division, 18th Brigade of the Australian 7th Division, four regiments of British artillery and some Indian, Polish and Czech troops.
One of those first-time-into-battle troops under his command at Tobruk was Western Australian, Private Walter John 'Jack' Darnley, 28, with the 2/28th Infantry Battalion signal platoon.
Part of the 24th Brigade initially assigned to the 8th Division but then reassigned to the 9th in Egypt, the 2/28th was raised from WA volunteers - many of them country boys, who signed up to "give Jerry a blood nose for threatening mother England".
Pte Darnley was probably of that mould.
He was born in Perth in 1912 just after his English parents arrived in WA and he signed up at Wiluna where he was an electrician at a gold mine.
Pte Darnley left behind wife Thelma, young daughter Connie and a son on the way.
Soon after he first dived into the Tobruk trenches, he received a card from Thelma telling him of son John's birth on April 4.
A resourceful man able to turn his hand to most things and also an accomplished musician "able to play any instrument", according to son John, 80, who lives in Geraldton, Pte Darnley left us with a poignant reminder of the siege of Tobruk.
It is a trench-made banjo, ingeniously constructed from materials mostly scrounged or found on the Tobruk battlefield.
Now fragile, with several strings broken and a tuning peg missing, it is on display in a showcase at the Birdwood House Military Museum in Geraldton, home of the Geraldton City RSL branch.
It was donated by his family as part of Pte Darnley's personal war service collection.
This collection also includes the card notifying him of his son's birth, a photograph of him and two mates in Beirut, Lebanon, in 1942, a number of songs and poems he wrote about his war experiences, a Japanese field telephone and a morse key for sending morse code.
After the Western Desert Campaign, Pte Darnley and the 2/28th fought along the brutal Kokoda trail in the New Guinea jungle, then went on to Balikpapan in Borneo where his active service ended when a bomb blew up a truck, shattering his legs and causing other serious injuries.
He spent 12 months recuperating at Hollywood Hospital in Perth before he was able to go home and meet his five-year-old son born while he was at Tobruk.
John Darnley said that before the war, when his father was prospecting near Menzies in The Goldfields, he supplemented what income he made from finding gold specks by playing in a band on Saturdays.
Mr Darnley has childhood memories of his father playing his trench banjo at frequent neighbourhood parties at his home after the war, as well as playing the organ, piano, violin and flute.
Pte Darnley named his trench banjo, which is about the size of a ukulele, the Darnley Dixaline.
The sound box was an army mess tin - known as a dixie, hence the instrument's name - covered with the skin from a drum Pte Darnley obviously found and thought no one would miss away from a parade ground.
The neck and peg head were made from pieces of scrap timber and tuning pegs were carved from pieces of wood, while the bridge supporting the strings was made from scrounged toothbrush handles.
Strings were the only things Pte Darnley could not source on the battlefield - he asked Thelma, who by then had moved back to her mother's home in North Perth with her children, to post some to him.
'The Darnley Dixaline Mk IV' is carved into the peg head - indicating there may have been other experimental predecessors - and a list of the locations and battles the 2/28th signal platoon were involved in, is carved along the fretboard, including 'Tobruk Garrison 26-3-41 to 23-9-41'.
As John Darnley points out, the most poignant thing about the Darnley Dixoline is that 29 members of his father's signal platoon signed the skin front either side of the strings.
"The sad part is, a lot of the men who signed it were killed later at Ruin Ridge," Mr Darnley said.
"My father wasn't there at that battle, he was in a field hospital away from the front."
"He'd had the top of a finger on his left hand shot off."
On the night of July 26 and 27, 1942, at a location known as Ruin Ridge in the first Battle of El Alamein, the 2/28th battalion lost 65 men killed and 490 captured, cut off behind enemy lines when British tank and infantry support failed to get through.
But the Allies stopped Rommel's advance through Egypt at that battle.
Three months later, in the second Battle of El Alamein, Allied forces began driving the Afrika Korps out of Egypt and back across Libya in what is now seen as a turning point in the Allies' fortunes with the first major defeat of German forces on land.
By denying access to Tobruk's port, Pte Darnley and his fellow Rats had a role in turning the war.
During the siege the Allies occupied 54 kilometres of open-topped trenches - construction was started by the Italians when they controlled Tobruk and completed by the Australians under Morshead - linking strong points protected by barbed wire and anti-tank ditches.
The trenches were arranged in a roughly semicircular double line through the Libyan desert to form a defensive perimeter about 11 kilometres out from the port to protect it from enemy artillery fire.
The job of soldiers, like Pte Darnley in the signals platoons, was to maintain communications between strong points along the trench perimeter, out to forward observation posts and back to field headquarters.
This meant running sheathed wire cables to link field telephones-- radio transmissions could alert the enemy and there was no point having forward observation posts unless observers peering into the desert haze and shimmering mirages, could report back what they saw.
It was the signalman's job to climb out of the relative safety of the trenches dragging a reel of cable to connect phones.
If, during an enemy bombardment, cables were severed, the signalman had to crawl on his stomach over the sand, with both enemy and friendly return fire above him, to reconnect or relay cables.
It was an extremely dangerous and important job.
After the two initial failed onslaughts by Axis forces, the siege of Tobruk became trench warfare, with the Allies and enemy dug in only about 365 metres apart in places.
Morshead at Tobruk created the example in modern warfare of offensive defence.
He commanded The Rats should control no-man's-land between the opposing forces, which they did, but it meant there was no let up for troops in the trenchs, with regular patrols beyond the perimeter, or for the signals platoons trying to maintain vital communications.
Morshead is reported to have bristled when a voice-over in a British propaganda newsreel about the siege, stated "Tobruk can take it".
"We're not here to take it, we're here to give it," he is reported to have thundered.
Being able to play a musical backing on the Dixaline during singalongs with mates in quieter moments between raids and counter raids along the Tobruk perimeter must have been a tremendous release from the constant pressures on troops and a scant relief from the ever-present reminder of the threat of imminent death.
Vietnam veteran, Geraldton City RSL president and Birdwood House Military Museum president Barry Stinson, about five years ago tried to trace the names on the front of the Dixaline through Army records and the Rats of Tobruk Association - two of those who signed, Thomas Kidd and Bill Marchant, were born in Geraldton and a third, HA Plummer, signed up in Geraldton.
Some had signed with nicknames and others had common names which made tracing them difficult or impossible, Mr Stinson said.
"We probably left it a bit late trying to trace them too.
"We didn't find anyone still alive whose name was on it, but through the association we did meet some of the 2/28th veterans - all now aged in their late 90s - who could remember hearing music coming from the signals platoon lines."
After returning to civilian life Pte Darnley went back to work as an electrician in the mines at Big Bell - now a ghost town near Cue - until he bought the powerhouse at Northampton and ran that for 13 years.
Plagued by poor health, Pte Darnley died in Perth in 1992, aged 79.
He never talked about his part in the siege of Tobruk or any other battles he took part in, John Darnley said.
"He would talk about all the tricks they used to get up to, all the things they did - like pinching a crate of beer from the officers' mess or posing as conductors on a tram and collecting fares while on leave in Cairo - but not about the war," Mr Darnley said.
The songs he wrote while in the Tobruk trenches include lines about "dodging shrapnel and bullets" and "tortured by sand storms and flies".
They are dismissive of the newsreel commentary about the soldier's life in Tobruk during the siege.
Like many returned servicemen of his ilk, Pte Darnley came back with an unquenchable thirst.
"I used to hear his nightmares but I never understood the drinking until much later," Mr Darnley said.
He said it was only after his own son Paul had served in the military in East Timor, Iraq and the Solomon Islands that he started to understand what his father had been through.
"I think he was drinking to forget, he was suffering from depression," he said.