A Peace Democrat during the Civil War, Bayard spent his early years in the Senate in opposition to Republican policies, especially the Reconstruction of the defeated Confederate states.

He sought increased cooperation with the United Kingdom of Great Britain and Ireland, working to resolve disputes over fishing and seal-hunting rights in the waters around the Canada–United States border.

[12] Thomas Bayard spoke at a public meeting in Dover in June 1861, saying that "with this secession, or revolution, or rebellion, or by whatever name it may be called, the State of Delaware has naught to do.

[14] By early 1862, the Delaware Guard came under suspicion of Southern sympathies, and Major General Henry du Pont, commander of the state militia, ordered it disarmed.

[23] In the Reconstruction Era, Bayard took up the cause of the defeated South, speaking against the continued military rule of the conquered states and advocating a return to civilian (and conservative) government.

[25] He spoke against each of the three Enforcement Acts, which increased the federal government's power to protect black Southerners' civil and political rights in the face of rising violence by the Ku Klux Klan and other groups.

[33] These United States Notes, popularly known as "greenbacks," had helped to finance the war when the government's gold supply did not keep pace with the expanding costs of maintaining the armies.

Grant's Treasury Secretary, William Adams Richardson, reissued $26 million of the redeemed greenbacks, reversing the administration's previous policy of removing them from circulation.

[40] Displeased with the result, Bayard nonetheless supported the Democratic nominee against Governor Rutherford B. Hayes of Ohio, the Republican candidate, speaking to large crowds in cities across the North and Midwest.

[63] Finally, Hayes signed an appropriation without the rider, but Congress refused to pass another bill to fund federal marshals, who were vital to the enforcement of the Force Acts.

[71] Meanwhile, in the House, Tilden supporter Clarkson Nott Potter of New York began an investigation into the 1876 election, hoping that evidence of Republican malfeasance would harm that party's candidate in 1880.

He remained popular in the Eastern cities for his conservatism and hard money beliefs, but many in the South, including Senator Augustus Hill Garland of Arkansas, advised Bayard to embrace silver to help halt the defections of Southern and Western Democrats to the new Greenback Party.

[77] After the party rift caused the defeat of the Democratic governor in New York's 1879 election, many Tilden adherents began to think their candidate could not win his home state, and drifted to Bayard, among others.

[78] Tilden's supporters attempted to weaken Bayard in February 1880 by publishing the speech he gave in Dover in 1861, in which he said that the United States should acquiesce in Southern secession.

[79] At the same time, Bayard's uncompromising stance on the money question pushed some Democrats to support Major General Winfield Scott Hancock, who had not been identified with either extreme in the gold-silver debate and had a military record that appealed to Northerners.

[92] Congressional Republicans also sought to deplete the surplus through a Rivers and Harbors Act that increased spending on internal improvements; Bayard opposed the bill and was gratified when Arthur vetoed it against his own party's wishes.

[94] In 1880, Democratic Senator George H. Pendleton of Ohio introduced legislation that required selection of civil servants based on merit as determined by an examination, but the bill did not pass.

[94] After the 1882 congressional elections, in which Democrats campaigned successfully on the reform issue, the Pendleton bill was proposed again, and again Bayard supported it, saying that "the offices of this Government are created ... for the public service and not for the private use of incumbents.

[109] Bayard filed a note of protest with the German government, and the three powers agreed to meet for a conference in Washington in June 1887, but they failed to achieve any agreement.

[111] As the threat of war grew, Bismarck backed down and agreed to another conference in 1889; two weeks later, a hurricane struck the harbor and all of the German and American warships were damaged or sunk.

The three powers agreed to a tripartite protectorate of Samoa with Malietoa Laupepa restored as king; that situation prevailed until 1899, when renewed civil war led to a second convention partitioning the islands between Germany and the United States.

[112] As Secretary of State the following year, Bayard hoped to again have free trade with Hawaii, and also endorsed the idea of establishing an American naval base there, although he preferred Midway Atoll to the eventual location, Pearl Harbor.

[117] Bayard led the American delegation, joined by James Burrill Angell, president of the University of Michigan, and William LeBaron Putnam, a Maine lawyer and international law scholar.

[120] Aware of the risk that the treaty might be rejected, Bayard and Chamberlain agreed on a two-year working agreement, allowing Americans to continue their fishing in Canadian waters by paying a fee.

[137] Bayard agreed with Cleveland and Gresham that the British were not attempting to reestablish their colony, but Nicaraguans (and many Anglophobic Americans) saw a more sinister motive, including a possible British-controlled canal through Nicaragua.

[139] The tension over Nicaragua soon abated, but the May 1895 death of Secretary Gresham, who like Bayard had favored cooperation with the British, led to increased disagreement over the Venezuela issue.

Olney's opinion, soon adopted by Cleveland, was that the Monroe Doctrine not only prohibited new European colonies, but also declared an American national interest in any matter of substance within the hemisphere.

[134] Olney drafted a long dispatch on the history of the problem, declaring that "to-day the United States is practically sovereign on this continent, and its fiat is law upon the subjects to which it confines its interposition ..."[141] Bayard delivered the note to the British Prime Minister (Lord Salisbury, who was also serving as Foreign Secretary) on August 7, 1895.

[151] Thirteen years after his death, the 1911 Encyclopædia Britannica said of Bayard that "his tall dignified person, unfailing courtesy, and polished, if somewhat deliberate, eloquence made him a man of mark in all the best circles.

"[5] In 1929, the Dictionary of American Biography described Bayard, as a Senator, as being "remembered rather for his opposition to Republican policies ... than for constructive legislation of the successful solution of great problems", and said that he had "the convictions of an earlier day ... and was never inclined, either politically or socially, to seek popularity with the country at large.