Change in Perception
The Napoleonic armies were initially welcomed as harbingers of liberty because they promised to bring about revolutionary ideals such as equality and fraternity to the countries they conquered. The people saw Napoleon as a symbol of liberation from oppressive monarchies and aristocracies.

Loss of Enthusiasm
However, this enthusiasm did not last long for several reasons:

1. Authoritarian Rule
As Napoleon consolidated his power, he began to rule as a dictator, suppressing freedoms and centralizing authority. His autocratic rule contradicted the ideals of liberty that the people initially associated with him.

2. Military Conquests
Napoleon's constant military campaigns and conquests led to widespread destruction and suffering in the countries he invaded. This resulted in resentment among the people who had once welcomed him as a liberator.

3. Economic Hardships
The Napoleonic wars brought about economic hardships as resources were drained to support the military campaigns. This led to increased poverty and discontent among the population.

4. Nationalism
As Napoleon's empire expanded, nationalist sentiments began to rise in various regions. People started to prioritize their own national identity over the ideals of liberty that Napoleon claimed to bring, leading to a decline in support for his rule.

Conclusion
In conclusion, the initial enthusiasm for the Napoleonic armies as harbingers of liberty waned due to Napoleon's authoritarian rule, military conquests, economic hardships, and the rise of nationalism. The people's perception of Napoleon shifted from a liberator to a tyrant, leading to a loss of the initial support and enthusiasm.