Their context is really important when you consider how it influenced the development of their opinion on whatever historical debate you're doing. Quick example the australian history wars- Windschuttle refused to acknowledge Indigenous oral histories as evidence, a position influenced by his empirical persuasions and training. While revisionist historians accept cultural history and alternative forms of historical records, empiricists generally do not, and as such their opinions significantly diverge.
As a general rule, only include information if it benefits your argument. Contextual information - when you present it in a critical manner and show how it applies to your debate - evidences a depth of knowledge and makes your argument that much more effective. Its a historiographical essay, not just historical- so show your analytical thinking and examine who your historians are and why they think the way they do. (Always go back to those 5 key questions!)
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