Of course, one has to wonder why those whose profession is the study[This is far off-topic for Telecom, so please keep followups to me privately.]
> of history tend to have liberal views. Is there something in the
> detailed study of what has happened in the past that leads to such a > position?
It should not be surprising that academia is skewed to the left, politically, although it was not always so. Conservatives tend to be people who define their success in terms which are more readily achievable in politics or in business than in academic research. It's a rare person who has the ability and desire to succeed in two realms.
Before the 1960s, university faculties were full of sort of academic conservatives we don't see too much any more: indolent white men from wealthy families who had no aptitude for business or law; this was reinforced by the popular social theories of the time. (In one documented example, most of Columbia's faculty supported Wendell Wilkie over Franklin D. Roosevelt.)