Final answer:
Many of France's allies experienced decline after the Peninsular War due to the enduring strain of conflict and Napoleon's mistaken strategies, which culminated in his defeat and abdication. The reformation of an anti-French coalition ultimately brought a decisive end to French dominance. The war's aftermath also saw a diminishing French influence on the European stage and in their colonial domains.
Step-by-step explanation:
After the Peninsular War, many of France's allies suffered significant consequences. The war had drastically undermined the power of France's allies due to the attrition of prolonged conflict and Napoleon's failed policies. Notably, the Spanish ulcer profoundly impacted France's military capabilities, with nearly 200,000 French soldiers' lives lost in Spain. The guerilla warfare tactics employed by the Spanish and the support from British forces led to a protracted and costly engagement for the French.
Following Napoleon's disastrous retreat from Russia, the anti-French coalition of Austria, Prussia, Britain, and Russia reformed. This alliance successfully defeated Napoleon's forces, leading to his abdication and the eventual restoration of the Bourbon monarchy in France.
Postwar, the French attempted to retain their colonial possessions, but movements like the resistance in Algeria showed the weakening grip of France on its empire.
Italy, which later emerged as a rival, and the marginal compensation France received after winning the Crimean War with Britain, illustrate the long-term weakening of France's geopolitical stance after the Napoleonic Wars, affecting its ability to influence its former allies and its position in Europe.