Short answers, pulled from the story.
Jacques Antoine Hippolyte Comte de Guibert died on the 6th of May 1790. He died practically of disappointment after facing attacks upon his return to the War Office on the eve of the Revolution.
The Essai général de tactique published in London in 1770 revolutionized how people thought about movement on the battlefield. This text placed immense emphasis on speed rather than rigid formations and was called the best essay on war produced by a soldier until 1871.
Jacques Antoine Hippolyte Comte de Guibert stood in the mud of Germany at age thirteen while watching his father Charles-Benoît lead troops during the Seven Years' War. His family moved through conflict zones as part of Maréchal de Broglie's staff during this period.
Jacques Antoine Hippolyte Comte de Guibert fell into disgrace because Count de Saint-Germain collapsed politically in 1777. This political collapse dragged Guibert down with him resulting in his relegation to a provincial staff appointment despite receiving promotion to maréchal de camp.
Jacques Antoine Hippolyte Comte de Guibert predicted that standing armies would become inadequate for great wars within twenty years of his death. He argued hegemony over Europe would fall to nations creating national armies instead and this prophecy came true as France moved toward conscription during the Revolution.