He had his heyday in the decadent Ancien Regime, the pre-Revolutionary monarchy, in which the nobility dominated France. He still looks back to those days with nostalgia and regret. Gillenormand believes that in modern times people lack the gift of living life to the fullest and enjoying all its pleasures. He raises Marius to believe that the Revolution "was a load of scoundrels" and he greatly disliked Napoleon and those that fought in his armies as well. He called them "brigands".
When Marius discovers that his father was a hero of the Battle of Waterloo and had fought in a number Napoleonic wars, and becomes a Bonapartist in politics, it causes a bitter break between them. He attempts to keep Marius from being influenced by his father, Colonel Georges Pontmercy. While in perpetual conflict over ideas, he does illustrate his love for his grandson.