Marx talks about this actually fairly in depth, primarily in ‘The Eighteenth Brumaire of Louis Bonaparte’ and ‘The Class Struggles in France, 1848-1850’. He talks about great power politics during the Springtime of Peoples and how various actions empowered various classes. Engels also discussed Prussia a lot, particularly in ‘Revolution and Counter-Revolution in Germany’ and ‘The Prussian Military Question and the German Workers’ Party’.

The tldr is the military was propped up by state planning and purposefully squashed liberal-bourgeoisie parties under Bismark, even going so far as to dismantling the Landtag to disenfranchise these groups. The military can therefore be seen as a pivot point for reactionary forces, and even centralized planning can be used to perpetuate, say, Junkerdom. A lot of German industry was made in spite of the aristocratic red tape, as part of the centralized mechanisms the army created, or as a solution to new contradictions in great power politics.

This relation was largely abolished by the Nazi revolution during the Weimar republic, they drew a lot of their support from the ‘middle classes’ re: the petite bourgeoisie and stocked the army with people from similar backgrounds. They also practiced Mussolini-style corporatism and gave the bourgeoisie direct political power with zero intermediaries. Many of these titans of industry piloted the Nazi war machine and were allowed to continue operations in West Germany. Check out their family histories, its interesting and can help paint a more clear picture of the rise of the bourgeoisie (some of the richest had fathers who were merely petite bourgeoisie artisans and small shop owners, and most got rich by catering to the Junker-centralized military-industrial complex).

https://en.wikipedia.org/wiki/Friedrich_Flick

https://en.wikipedia.org/wiki/Günther_Quandt

https://en.wikipedia.org/wiki/August_von_Finck_Sr.

https://en.wikipedia.org/wiki/Freundeskreis_der_Wirtschaft