It's not just history in which this problem lies. Much of the study of literature is based on personal observation and interpretation. For instance, tone and mood. Of course, if you're reading about a tragic historical event, to say it made you happy might be a stretch. But, there are many things that could make you feel. You could feel pity or anger or sympathy or empathy or indifference (hopefully not indifference). A one-word answer can't always define the way you, personally, thing. This is what makes English lit one of the most complex and beautiful subjects (speaking of opinions). There's not always a right or wrong answer as long as you provide a sufficient basis for your answers.
I'm not saying that all test should be essays and ask you why you think something is true or false, I just think it's important to understand that there's more than one point of view in every case (other than proven fact).
The hardest part (as always) is making a change that won't just make your students hate you or stress even more. No one needs that. What they need is an opportunity to argue a point of view without fearing punishment. I wrote a few comments on one of my tests expecting to recycle the paper immediately after the test, but I had to erase them because he was collecting the test and I was afraid that they were too snarky. I don't regret this decision; they were very snarky comments. The point was, I was very frustrated with the nature of the test and I wanted to argue the points that I could never articulate in class. I think the ability to provide insight and discussion is very important in a classroom and it's hardly ever provided.
I wrote all of this in the time I had right after one of my midterms, so I never really came to a conclusion. The point I was trying to make through all of my frustration, is that true and false aren't always the only answers. No student should be given a 50% chance of getting something right.
A/N: All test question examples are hypothetical