Do Actors/Actress's who play roles from history truly understand those they portray in the messages in speeches delivered on screen?

I am working and needed a break. I can her my wife watching the movie "The Alamo: 13 Day of Glory" with a young Alec Baldwin and seasoned actors like Brian Keith and James Arness. Hollywood again recants the historic story of the heroes of if this little mission that stood between a yet to be prepared Sam Huston and the might Mexican Army under Santa Anna.

I hear Alec Baldwin give what is reported to be a speech to those men who knew they were going to die. There are many volumes on the battle at The Alamo. So I am not going debate various facts. But, listen this clip. It is > 11 mins. But, advance the time index to ~3:50. Then listen to the nearly 1:15 min speech that ends around time index of 5:05.

https://www.youtube.com/watch?v=3Ge7SWgLytI

It caused to to think about the men and women in Hollywood and how much they do or don't understand the consequence of the men and women the portray. I have always found it interesting how a role would have been portrayed had someone else been cast. But, in the remake of the earlier John Wayne version I found it interesting to consider in Alec Baldwin once the film was over, truly understood the man behind the role he was ACTing.

So, my question is this for the RP family:

Do those who play roles from figures in history truly understand the gravity of these roles and do they reflect on those roles at times in current history for perspective in addition to the actual historical records before they speak about current events?

Note: History is always being revised because new "tangible" evidence is being unearthed, so I am OK with changes to the historical record, so long as these are fair and balanced presenting "the good, the bad and the ugly" from this new knowledge.

As always, this question is LOADED and some will not take kindly to it being asked and they will undoubtedly take the intent of the question in negative directions; however, by asking the question can reveal some other underlying insights when considering this questions with perspective. In your responses, please be factual and honest. Not everyone in Holly is good or bad. They are human beings like any of us here on RP. How ever some act as those they are practicing a form of behavior that I DO NOT cotton to by acting as if they are "...more equal than..." others.