Did you go to the Shipka peak, where there is a memorial of the men who died there? Probably this is the place of which Bulgarians are most proud of - during the Russian-Turkish war which ended in Bulgaria's liberation, there were Bulgarian militiamen fighting alongside the Russians and the fight for the Shipka pass was one of the most important, bloody fights where the Bulgarians and a small contingent of Russian troops successfully defended the pass for a few days from greatly outnumbering Turkish soldiers. It is said that they even depleted their ammunitions and used rocks and bodies of dead fellows to through upon the advancing Turks. This turned out a decisive moment in the war because the Turks couldn't reinforce the besieged town of Pleven. I think the celebrations for the Liberation day (3rd of March) are always held there.
For some further reading, you could look here and then follow the link on the page for the actual battles:
http://en.wikipedia.org/wiki/Shipka_Pass