Man of Straw -- also translated as The Loyal Subject -- is a razor-sharp take-down of the upper middle class buffoons who fervently supported Kaiser Wilhelm --the same type of power-worshipping nativists who later embraced the Third Reich. The subject in question is Diederich Hessling, who spends his college years swilling beer with his frat brothers in their exclusive secret society, the "Neo-Teutons" (ha!), and avoiding any type of intellectual pursuits, while challenging anyone and everyone to duels of honor (but not going through with those duels, of course; just issuing the challenges!). He worships the military, but desperately tries to avoid service by pulling strings with his social connections to get a medical discharge by feigning minor health problems. (Weak bones! A flat foot!)
It's obviously a portrait of Wilhelm himself, as Mann (older brother of Thomas and uncle of Klaus) describes Diederich as looking very much like the emperor, even shaping his mustache upward in sharp right angles in imitation of the Kaiser. But it's also a portrait that has universal application, at times so accurately depicting certain modern American conservative warhawks and chickenhawks -- everyone from Donald Rumsfeld to Donald Trump, but also their lackeys, like Chris Christie and Ted Cruz -- that we begin to see Mann's brilliance in crafting this character: these politicians, like Diederich, are not great men. They are, by and large, average dolts. The fact that Diederich looks, speaks, and acts like such national leaders (Wilhelm specifically) undercuts their perceived authority. These political figures, for all their pomp, lofty rhetoric, and gilded lives, are no more than uncouth, half-educated blowhards. And on some level, they know it.
Mann is quite clear on the dangers of authoritarianism and the kind of people it attracts. His portrait of Diederich might well describe any extreme-right politician (or supporter) of this day. Deiderich isn't too bright and is physically a coward, but his wealth and status as the son of a industrial owner gives him both privilege and a superiority complex. He lacks empathy and sees women merely as objects for his temporary pleasure or social status, and so his marriage becomes a business deal (and a poor one, at that), with a constant, paranoid fear of blackmail hanging over his head, as in most of his affairs. He is a mamma's boy who talks bravely about the military and about wanting to "duel" those who dishonor him, but who cringes at any possibility of confrontation. His love of power causes him to worship anyone who wields it and to fall in line behind anyone who commands it, without question. He follows the Church not because he believe in its values, but because it gives him status and further scapegoats the "Others" who are not Christian. (In the case of Germany under Wilhelm, the Jews.) His wealth and status as a leader of industry are entirely inherited, so he knows nothing about the business he owns. As a result, he takes out his anxiety and aggression on his workers, who are brighter than him, but lower in class, so are unable to advance. He fears them, but his ego prevents him from acknowledging this fact.
This complex combination of physical weakness, willful ignorance, hyper nationalism, capitalistic exploitation of the lower classes, and worship of military power creates "the loyal subject": one who will be attracted to any powerful force upon which he can project his idealized (and unachievable) Self as a way to substitute for his own lack of will and inner fortitude. He will follow anyone who advocates crushing or eliminating the weak or "undesirable," not realizing that 1) these are his own flaws that his ego refuses to acknowledge within himself, and 2) he is supporting the very power-hungry authorities who will not think twice about crushing him as one of the weak. His own insecurity and lack of self-worth causes him to act against his own self-interest, but in the end, because of his inherited wealth, status, and privilege, he survives -- and even thrives -- safe in the bubble of his own foolish ignorance.