[427] Sumner sent the treaties for a full Senate vote, while Grant personally lobbied other senators. Despite Grant's efforts, the Senate defeated the treaties, on Thursday, June 30, by a 28–28 vote when a 2/3 majority was required.[428]
Grant was outraged, and on Friday, July 1, 1870, he sacked his appointed Minister to Great Britain, John Lothrop Motley, Sumner's close friend and ally. [429] In January 1871, Grant signed a joint resolution to send a commission to investigate annexation.[430] For this undertaking, he chose three neutral parties, with Fredrick Douglass to be secretary of the commission, that gave Grant the moral high ground from Sumner.[431] Although the commission approved its findings, the Senate remained opposed, forcing Grant to abandon further efforts.[432] Seeking retribution, in March 1871, Grant maneuvered to have Sumner deposed of Sumner's powerful Senate chairmanship, replaced by Grant ally Simon Cameron.[433] The stinging controversy over Santo Domingo overshadowed Grant's foreign diplomacy.[413] Critics complained of Grant's reliance on military personnel to implement his policies.[423]

Cuba and Virginius Affair
Main article: Virginius Affair
American Captain Frye and his crew were executed by Spanish authority.
