偉大な政治家であった

was a great politician

→ 偉大だ
phrase Rare #26,604
was a great politician A formal or literary way to say 偉大な政治家だった. であった is the past form of the copula, meaning “was.”
JA: 彼は日本の歴史に残る偉大な政治家であった。
EN: He was a great politician who went down in Japanese history.

彼は偉大な政治家であったと思われている

He is thought to have been a great statesman.

彼が偉大な政治家であったと言う事実は否定できない

The fact that he was a great politician cannot be denied.

彼は偉大な政治家であったそこで大統領に選ばれた

He was a great statesman, so he was elected president.