Lord Ronald Rust, or "Ronnie" is the current patriarch of the Rust family; one of the older noble families in Ankh-Morpork, the most powerful city-state on the Sto Plains. He comes from a long line of military men, most of whom are incompetent in the true British Army tradition. He is a caricature of all the supercilious aristocratic snobs of movies, novels, and real Roundworld life - conflicted by greed and vanity on one hand, and patriotism and "doing the right thing" on the other. He is arrogant and ignorant and a very dangerous military commander; he expects huge casualties, and if they are his, c'est la guerre. He has been described as operating on the principal that any battle where you can deduct your casualties from the casualties suffered by the enemy and get a positive number is a glorious victory - a common philosophy in the Napoleonic Wars as well as WWI.
The first Lord Rust was created a Baron after single-handedly killing thirty-seven Klatchians while apparently armed with nothing more than a pin. Another ancestor, Lord Albert Rust, is distinguished with a civic equestrian statue, despite not having won any battles nor having brought too many men back with him. When His Grace, Sir Samuel Vimes rails against the bloated and blighted aristocracy, it is Lord Ronald Rust who is front and center in his mind.
While initially strong monarchists, the Rust family has adjusted well to the monarchy's collapse and the subsequent rise of the merchant class and its Guilds. Ronald was one of the noblemen invited by Edward d'Eath to plot the restoration of the monarchy but decided not to become involved since he was doing quite well under the present dictatorship by making money as a slum landlord. He is described as the gentleman who looks so leisurely that he seems to be sleeping during important meetings. Sam Vimes' wife, Lady Sybil Ramkin, dated him for a little while when they were both younger, once remarked that Lord Ronald Rust was rather a wet fish.
In the novel Night Watch, which takes place during the Glorious Revolution, he was a young captain who was put in charge of one of the Watch Houses. Rust's aptitude for tactical thought and leadership is summed up by Vimes' evaluation of him during that period: "the gods' gift to the enemy, any enemy, and a walking encouragement to desertion." This is the beginning of a long military career in which Vimes' assessment has no reason to change. He becomes well known for his ability to accomplish little with great loss of life within his own troops. In Monstrous Regiment, where Ankh-Morpork intervenes in the war between Borogravia and Zlobenia, Vetinari puts Rust in charge of Ankh-Morpork's military contingent and makes him only second-in-command of the whole expedition - the command, as well as sole direction of the political and diplomatic contingent, going to Sam Vimes, a far superior diplomat. This strategy on the part of Vetinari effectively prevents any lingering ambitions that Rust, in charge of a small army, might have entertained for taking over the Patricianship. In Jingo, during the "almost war" with Klatch over the island of Leshp, Lord Rust assumed command of the Ankh-Morpork forces and even became the official leader of the city, but once again he demonstrated his usual ability and it was left to Vimes to resolve the conflict properly without further loss of life.
In Snuff, Vimes meets his old adversary once again when he finds that the Rust family own a second property, the family's country seat of Hangnails, in the same general area as Crundells, Vimes' country estate, where Rust and his son are currently in residence "on business". Vimes is shocked to see how much Rust has deteriorated physically: he is now wheelchair-bound and on the long downhill slide toward his meeting with Death. There is therefore an uneasy truce between them, anything more likely is impossible. Clearly the invalid Rust is not much of threat to either Vimes or the Patrician, even after his brief stint as Patrician.
Rust has three children. His heir apparent is the very unpleasant Gravid Rust, described by Colonel Charles Augustus Makepeace as a greasy lad with a name like a pregnant frog (which gravid does mean). Nobody who bred fish or dragons would ever call a son that; but, as the Colonel observed, Ronald Rust is not the kind of man to open up a dictionary and look things up. Gravid was brought before the Patrician for shooting a servant for laying out his shoes the wrong way round. Vetinari describes him as an "ignorant, arogant, pompous idiot". In Snuff, Gravid enslaves goblins to work on his tobacco plantations and is involved in smuggling Troll drugs so, after being exposed by Vimes, is exiled to Fourecks. Rust also has at least one daughter, Regina, described by Vetinari as a ferocious woman, very difficult and hot-headed... but smart" She is expected to inherit the family estates and name, when an accident involving native poisonous arachnids befalls Gravid while he is exiled in Fourecks.
Some sources suggest that he third child, Charles, is a bit of an anomaly or continuity problem, but it is more likely that he is simply dead by the time of the events of Snuff. In the novel Snuff, it is clear that Gravid Rust is the only son of Lord Rust, and that on his future demise at the bite of the Fourecks spider, the succession will go to his sister Lady Regina. However, in the section of the Discworld Fools' Guild Yearbook and Diary 2001 dealing with the espionage and intelligence-gathering function of the Fools' Guild, there is a reference to The Honourable Charles "Charlie" Rust, explicitly described as "the younger son of Lord Rust". It is mentioned that Charles had a gambling problem and had borrowed $100,000 from Chrysoprase to cover his gambling debts - never a good move if longevity is a goal. Needless to say, he was unable to pay the debt and the intelligence notes observe that his father, Lord Rust, was in no position to assist because his mercantile fleet had suffered serious attrition for various reasons and the family finances had been considerably impaired as a result - perhaps this led to his son Gravid trying to reestablish the family fortune quickly as outlined in Snuff. In the Fool's Guild Yearbook it is strongly hinted that Charlie is dead, not surprising given Chrysoprase's lack of charity toward people who owe him money.
Apart from his family, Lord Ronald Rust had a favourite junior officer who becomes something of a crony, Colonel Edgehill.
As stated above, Lord Ronald Rust is very reminiscent of that upper class military leader prevalent in the British army particularly present up to and including the Crimean until which time officers bought their commissions and came from the upper classes (still evident to a lesser extent during WWI as well). Pratchett likely modeled him in speech, manner and description, on Lord Cardigan, who led the Light Brigade in that renowned and ill-conceived headlong dash against Russian artillery at the Battle of Balaclava(1854) which was immortalized in Alfred Lord Tennyson's poem The Charge of the Light Brigade.
Cardigan has been described as a" typical son of privilege, a baying, drawling, affected dandy not over-burdened with brains, who effectively bought his way up the ladder of rank in the British Army". He was one of the explicit reasons why Garnet Wolseley reformed the army promotional system to one involving a completely professional officer class that would, at least in theory, be selected and promoted on merit only. In practice, Wolseley was only partially successful in his reforms as considerations, such as background, social standing, type of education and independent means over and above the official pay scale, are still important considerations in certain corps and regiments of the British Army today. Lord Cardigan's horse was nomed "Ronald", a famous charger bred on Cardigan's Deene Park estate. Knowing Pratchett's style, this is likely not a coincidence.
There are also many other incompetent military leaders whose actions make up the kind of military 'genius' present in Ronald Rust's character. There are striking similarities with the life, attitudes and military proficiencies of George Armstrong Custer, who was the same sort of affected dandy, with milky-blue eyes and long blonde hair of which he was vainly proud, even when it became thin and grey. He also led a cavalry regiment to destruction in an impetuous and ill-considered charge against superior odds at the Battle of Little Bighorn. Both Cardigan and Custer achieved lasting fame after their deaths. The public initially saw them as tragic military heroes and exemplary gentlemen who sacrificed their lives for their countries. However, more recently their arrogant stupidity has been exposed. In Custer's case, President Grant himself said, "I regard Custer's Massacre as a sacrifice of troops, brought on by Custer himself, that was wholly unnecessary – wholly unnecessary. Today both are remembered as epitomes of vainglorious incompetence.
There was also a Bernhard Rust who served as Hitler's Reichsfuhrer for Education and Science. By all accounts neither a sympathetic man, nor especially intelligent, he was not a great leader or administrator and his underlings were kept constantly busy compensating for his errors and preventing German education from being abased. This Rust was also obsessed with the purity of the German language and the perceived need for all German children to be taught correct grammatical forms and spellings. His life's work was to create a single standard form of High German that would supersede all the little quirks and differences of the myriad dialect forms. He was frequently thwarted in this by people who told him that Germany had other rather more pressing things to worry about, like losing the war. Whether Pratchett knew of this man is unknown but, as an interesting aside, this Rust was, literally, a Grammar Nazi.