Complex sentence: Radford was relied on by Navy leaders as an expert who would fiercely defend the Navy's interests from budget restrictions, but his appointments were opposed by Fleet Admiral Chester Nimitz, who feared his hard-line stance on the budget would alienate the other branches.
Split into simpler sentences: Radford was relied on by Navy leaders as an expert who would fiercely defend the Navy's interests from budget restrictions. These appointments were opposed, however, by Fleet Admiral Chester Nimitz, who feared his hard-line stance on the budget would alienate the other branches.