In a general sense, World War I and World War II were wars conducted on a massive scale unlike any other wars in history. They were similarly caused by nationalism, imperialism, alliances, and militarism. Both wars saw countries trying to upset the power balance in Europe for their own gain.
To cause a source to be biased means that it is influenced by your opinion or another factor that is not factual. Bias can take away from the credibility because it is not completely true, as a source should be.
The only people allowed to vote was Wealthy land-owners who were white and male. If you were not all these, you were disqualified. I hope this helps!
