To define the words properly, you have to determine in which society and at what time.

For instance, an American conservative would have had a particular hatred for Soviet hardliners during the Cold War. The same would have been true of a Russian liberal during the same period, whereas a Russian conservative would have been the Soviet hardliner. ;-)

Wars are instigated and fought enthusiastically by the arch-conservatives on either side of the conflict. They are very loyal to military tradition and they rely on it heavily, while the liberals on both sides of a war are somewhat less inclined to do that...and more inclined to question whether a war is the best way of dealing with the situation.

Conservatives, in other words, are born to go out and kill other conservatives, while liberals are born to write books and songs and make movies which exhaustively analyze the futility of war. ;-)