Why would davids painting have been important to the leaders of the french revolution?

It demonstrated the importance of loyalty to one's country.

During the French Revolution day, with painting of great importance for leaders, it had the Martyrs of the war been painted on tapestry.

Explanation:

He followed classical themes on huge canvases and he was a really popular and celebrated artist during the French Revolution. During French Revolution his paintings that painted leaders and Martyr had a more realistic approach and hence it was a very famous among the Great people of the society.