Complex sentence: During Foraker's first term in the Senate, he had done legal work for Standard Oil; in the letters, Archbold made reference to legislation he considered objectionable, and also made references to substantial fees to Foraker.
Split into simpler sentences: During Foraker's first term in the Senate, he had done legal work for Standard Oil. In the letters, Archbold refered to legislation he considered objectionable, and also mentioned the substantial fees to Foraker.