History can be fact and critical thinking. Most of the history we know today was written by the victors. However, that does not mean history is presented without facts.
Eye witness testimony can be far different from facts. 5 eye witnesses can witness a multiple homicide. They could tell the story in 5 different ways. However, the end point is someone killed x number of people. That is a fact.
While some parts of history are conjecture, such as intent/motive/cognitive planning, some parts of history are facts. Distribution of troops, commodities and territories can be objectively stated.
One of my favourite professors in university always taught his history classes as x number of stories. The history of modern China was a 13 story class. He gave you facts, but constantly encouraged critical thinking. When it comes down to it, the study of history is about asking questions and using facts to try to reason out an answer to the best of our abilities.