Ironically, the caning that Massachusetts Senator Charles Sumner received from South Carolina Representative Preston Brooks on May 22, 1856 may well have been the best stroke of good luck that Sumner ever received, rescuing his senatorial career and ultimately transforming him into one of the most powerful men in the country.
Sumner was first elected to the United States Senate by the Massachusetts legislature in 1851 as the result of an unstable and transitory coalition between Democrats and Free Soilers. No party at the time had a majority in the state. At the beginning of 1851, Massachusetts Free Soilers - heretofore primarily a group with more connections to the Whigs than to the Democrats in Massachusetts - struck a deal with the Democrats:
With Free Soil backing, the Democrats would elect their candidate for governor, George S. Boutwell, the lieutenant governor, the speaker and other officers of the [state] House of Representatives, a majority of the governor's counsel; in addition they would receive the short-term United States senatorship, the few remaining weeks of [Daniel] Webster's term which [Robert C.] Winthrop was filling.
The quid pro quo included the other Senate seat, which would go to Sumner:
The Free Soilers would get the presidency of the state senate, the remaining members of the governor's council, and the six-year United States senatorship, commencing March 4 . On January 7 , a Free Soil caucus, by a vote of eighty-four to one, nominated Sumner senator, and the following day the Democrats, with only six dissenting votes, accepted him.
But even with this deal, Sumner's election was a close-run thing. In the legislative voting, a large majority of the Whigs unenthusiastically but steadfastly supported Winthrop. More important, a faction within the Democratic Party, led by Caleb Cushing and former governor Marcus Morton, "objected to sending 'a red-hot Abolitionist, . . . like a firebrand, for six years, into the senate chamber of the United States.'" Although Sumner was tantalizingly close, he was a few votes short.
The legislature remained deadlocked for over three and a half months (from early January to late April 1851). Ultimately, Sumner was elected "with a majority of precisely one" vote:
On April 24  the legislature reassembled in an atmosphere of great tension. On the twenty-fifth ballot there were again two more votes than there were representatives present [there had been prior irregularities]. After much wrangling, the house adopted a Whig proposal that on future ballots each member must cast his vote in a sealed envelope, so that it would be impossible for these extra ballots to be slipped in. Shortly after noon, the twenty-sixth ballot was taken. This time Sumner received 193 of the 385 votes cast, a majority of precisely one, and was declared elected.
Having been elected by a paper-thin majority, Sumner soon saw the coalition that elected him fall apart, for both internal and external reasons. In the 1852 and 1853 elections, the coalition was defeated by the Whigs, the second "time so decisively that the plan for Free Soil-Democratic fusion in Massachusetts was finally abandoned." The Whigs, in charge of the state government, elected Edward Everett to the other senate seat.
Then in 1854 the Know-Nothing tidal wave hit Massachusetts. Democrats, Whigs, Free Soilers and the new Anti-Nebraska proto-party alike were swept away in the deluge. The Know-Nothings emerged with the governorship, an overwhelming majority in the state legislature, and the U.S. Senate seat not held by Sumner:
[Former Conscience Whig and Free Soiler Henry] Wilson . . . had thrown his strength behind Henry J. Gardner, the Know-nothing candidate for governor. In return he secured a pledge that, if successful, the Know-nothings would elect him to the Senate as Sumner's colleague. Gardner received an unprecedented majority of nearly 33,000 votes, and the new legislature consisted of one Whig, one Democrat, one Republican - and 377 Know-nothings.
Although the Know-Nothing tide ebbed somewhat in 1855, the Know-Nothings remained firmly in charge of the state. "In 1855, as in the previous year, the new [Republican] party made a poor showing in the polls, and Gardner, combining nativism and Whiggery, was re-elected."
In short, by the end of 1855 - and the Congressional session beginning December 1855 was the last in which Sumner had a chance to make an impact before he would be up for reelection in early 1857 - Sumner's political base had disappeared. For all the latent anti-slavery sentiment in Massachusetts, the old coalition had fallen apart and there was no sign that the new anti-Nebraska coalition would gel anytime soon. Many former Whigs detested him and Democrats felt no loyalty for him. Governor Gardner was eying the Senate seat and "plot[ting] to stage a premature election of [Sumner's] successor." Sumner looked like a political goner.
"Providentially, a burning issue came to hand" that saved Sumner from likely defeat. At the beginning of January 1856 Democratic Senator Stephen A. Douglas of Illinois introduced the Kansas-Nebraska Act, which gave Sumner the opening to deliver his The Crime Against Kansas speech on May 19 and 20, 1856. Two days later, on Thursday May 22, 1856, South Carolina Representative Preston Brooks administered his famous caning of Sumner - and created a "senator for life":
Sumner's friends used Massachusetts indignation over the assault to bolster his shaky political prospects. The news of the attack reached Boston just in time to give Sumner's supporters a face-saving victory over Governor Gardner, who was trying to emasculate the personal liberty law Sumner had helped draft. By astute management Republicans forced through the legislature resolutions not merely condemning Brooks's actions, but endorsing "Mr. Sumner's manliness and courage in his earnest and fearless declaration of free principles, and his defence of human rights and free territory." [Future wartime Republican governor] John A. Andrew almost gave the game away when he blurted out at the Faneuil Hall rally that in order to secure "liberty of speech - nay, liberty itself," Sumner must be re-elected, for Republicans were unobtrusively working toward precisely that end. "Providence itself seems to be on the side of the republican party," [Sumner's estranged former law partner George S.] Hilliard lamented. "Sumner is not merely their champion but their martyr, and his election for the next six years is now certain." A New Yorker, more prescient, declared that Sumner "is made by this act, senator for life."
After that, Sumner's reelection was almost a foregone conclusion. When the new state legislature met in January 1857,
the Republicans in the [state] House of Representatives forced a vote on January 9, even before Governor Gardner [who had once again been reeelected] could send in his inaugural message, which they feared might contain distracting proposals. Out of the 345 votes cast, Sumner received all but twelve. Four days later, against protests over their unseemly haste, Republicans in the [state] Senate adopted a rule for viva-voce voting on the senatorial election, and, as public opinion could thus be brought to bear upon each member, Sumner received the unanimous vote of the upper house.
In his book Charles Sumner and the Coming of the Civil War (from which all quotes in this post are taken), Prof. David Herbert Donald sums up Sumner's stroke of good luck:
Candidate of a minority party, [Sumner] was first chosen to the Senate through the devious workings of a political coalition. At nearly any point during his first five years in office, had he been up for re-election, he would almost certainly have been defeated. Then Preston Brooks's attack gave him his second term in the Senate and thereby assured him seniority and prestige within the Republican party. Never chosen by direct popular vote for any office, Sumner, by 1861, nevertheless had become one of the most powerful men in the United States.