Oliver Hazard Perry Throck Morton (August 4, 1823 – November 1, 1877) was a U.S. Republican Party politician from Indiana. He served as the 14th Governor of Indiana during the American Civil War, and was a stalwart ally of President Abraham Lincoln. During the war, Morton suppressed the Democratic controlled Indiana General Assembly. He exceeded his constitutional authority by calling out the militia without approval, and during the period of legislative suppression he privately financed the state government through unapproved federal and private loans. He was criticized for arresting and detaining political enemies and suspected southern sympathizers.

During his second term as governor, and after being partially paralyzed by a stroke, he was elected to serve in the U.S. Senate. He was a leader among the Radical Republican reconstructionists, and supported numerous bills designed to punish and reform the former Southern Confederacy. In 1877, during his second term in the senate, Morton suffered a second debilitating stroke that caused a rapid deterioration in his health; he died later that year. He was mourned nationally and his bier was attended by thousands before his burial in Indianapolis's Crown Hill Cemetery.

Morton was an Indiana native born in Wayne County near the small settlement of Salisbury on August 4, 1823. His family name, Throckmorton, had been shortened to Morton by his grandfather, but the males in the family carried Throck as a middle name. He was named for Oliver Hazard Perry, the victorious admiral in the Battle of Lake Erie. He disliked his name from an early age, and before beginning his political career he shortened his name to Oliver Perry Morton, from Oliver Hazard Perry Throck Morton. His mother died when he was three, and he was raised by his maternal grandparents. He spent most of his young life living with them in Ohio.

Morton and his older brother did not complete high school, but together they apprenticed to become hat makers. As a teenager, he moved to Centerville, Indiana, to take up his trade. After four years in the business he became dissatisfied with his profession and decided to instead pursue a career in law. He enrolled at Miami University in 1843 and studied there until 1844. He then briefly attended Cincinnati College to continue his law studies. In 1845 he returned to Centerville where he was admitted to the bar. He formed a law practice with Judge Newman and became a successful and moderately wealthy attorney. Morton married Lucinda Burbank the same year he returned to Centerville; together the couple had five children, but only two survived infancy.

In 1852 Morton, at the urging of Judge Newman, campaigned and was elected to serve as a circuit court judge but resigned after only a year; he found that he preferred practicing law. Morton had been a Democrat for all of his adult life, but living in a region dominated by the Whig Party he had little hope of any political career without a change of party.

After the repeal of the Missouri Compromise the Democratic Party began to go through a major division and Morton sided with the anti-slavery wing. With the passage of the Nebraska-Kansas Act, the state party began to expel anti-slavery members, including Morton. Morton, along with many other expelled and disaffected Democrats joined the Know-Nothing Party in 1854 and ran as its candidate for governor against Ashbel P. Willard, but was defeated. He switched parties again and moved to the Republican Party following the collapse of the Know-Nothing party. He was one of the founders of the Republican Party, serving as a delegate to the 1856 Republican Party Convention in Pittsburgh. His speeches against slavery made him popular among the party in Indiana. He was noted for his "plain and convincing" manner of speaking, his contemporaries said he was not "eloquent or witty", but rather "logical and reasonable". He was nominated to be the Republican candidate for Governor of Indiana that year, winning a unanimous vote at the state convention. Despite a hard fought campaign, he lost the general election to Democratic state senator Ashbel P. Willard.

The Republicans nominated Morton for lieutenant governor in 1860 on a ticket with the more popular Henry S. Lane as governor. The two men were both popular in the party, and neither wanted to run against the other in the convention primary and damage their chances for victory in the general election. The party leaders had arranged that upon their victory, the General Assembly would elect Lane to the U.S. Senate and Morton would become governor, assuming that the Republicans took control of the assembly. The campaign was long and focused primarily on the prevailing issues of the nation and the looming possibility of a Civil War. The day after the inauguration, Lane was chosen by the General Assembly for a senate seat. He resigned immediately and Morton succeeded to become governor.

Morton served as governor of Indiana for six years (1861 – 1867) and strongly supported the Union during the Civil War. He raised men and money for the Union army, and successfully suppressed Indiana's Confederate sympathizers. During his early tenure as governor, Morton believed that war was inevitable and began to prepare the state for it. He appointed men to cabinet positions who were well known to be against any compromise with the southern states. He established a state arsenal and employed seven hundred men to produce ammunition and weapons without legislative permission and made many other preparations for the war to come. When open war finally broke out on April 12, 1861, he telegraphed President Abraham Lincoln three days later to announce that he already had 10,000 soldiers underarms ready to suppress the rebellion. Lincoln and Morton maintained a close alliance during the war, although Lincoln was wary at times of Morton's ruthlessness. Lincoln once said of Morton that he was "at times the shrewdest person I know." Morton went to great lengths to ensure that Indiana was contributing as much as possible to the war effort. Governor Morton wrote to Lincoln claiming that "no other free state is so populated with southerners", and that they kept Morton from being as forceful against secession as he wanted to be. In 1862, he attended the Loyal War Governors' Conference in Altoona, Pennsylvania, organized by Pennsylvania Governor Andrew Gregg Curtin, that gave Lincoln the support needed for his Emancipation Proclamation.

Morton was able to keep the state united during the first phase of the war, but once emancipation became an issue in 1862 the Republicans suffered a major defeat in the mid-term elections, and he lost the support of the strong Democrat majority in the legislature. Before the new legislature had met, Morton began circulating reports that they intended to secede from the Union, instigate riots, and were harboring southern spies. The atmosphere created by the accusations only worsened tensions between the two parties and guaranteed a confrontation, which was probably already inevitable. Morton had already made several unconstitutional moves, including the establishment of the state arsenal and the Democrats decided to attempt to reign him in. When the legislature sought to remove the state militia from his command and transfer it to a state board of Democratic commissioners, Morton immediately broke up the General Assembly. He feared that once in control of militia, the Democrats may attempt to overthrow him and secede from the Union. He issued secret instructions to Republican legislators, asking them to stay away from the capitol to prevent the General Assembly from attaining the quorum needed for the body to pass legislation. With Morton's aid, the Republicans fled to Madison where they could quickly flee into Kentucky should the Democrats attempt to forcibly return them to the capitol.

No appropriations bill had been passed yet, and the government quickly neared bankruptcy. The Democrats assumed that Morton would be forced to call a special session and recall the Republicans to fix the situation, at which time they could again press their measures to weaken the governor. Morton was aware of their plans, and acted accordingly. Going beyond his constitutional powers, Morton solicited millions of dollars in federal and private loans. His move to subvert the legislature was successful, and Morton was able to privately fund the state government and the war effort in Indiana. James Lanier gave Morton funds to pay for maintenance on the state's debt until the state could being collecting revenue again. There was considerable rage among the Democrats, who launched a vicous attack on Morton who responded by accusing them of treason. Following the suppression of the General Assembly in 1862, Morton asked General Henry B. Carrington for assistance organizing the state's levies for service. Morton established an intelligence network headed by Carrington to deal with rebel sympathizers, the Knights of the Golden Circle, Democrats, and anyone opposed the Union war effort. While Carrington succeeded in keeping the state secure, his operatives also carried out arbitrary arrests, suppressed freedom of speech and freedom of association, and generally maintained a repressive control of the southern sympathetic minority. In one incident, Morton had soldiers disrupt a Democratic state convention in an incident that would later be referred to as the Battle of Pogue's Run. Many leaders of the Democratic Party were arrested, detained, or threatened. He urged pro-war Democrats to abandon their party in the name of unity for the duration of the war and met with some success. Former governor Joseph A. Wright was among the Democrats that had been expelled from the party, and in an attempt to show his bipartisanship, Morton appointed him to the Senate.

In reaction to his actions cracking down on dissent, the Indiana Democratic Party called Morton a "Dictator" and an "Underhanded Mobster" while Republicans countered that the Democrats were using "treasonable and obstructionist tactics in the conduct of the war". Morton illegally — without approval from the legislature — called out the state militia in July 1863 to counter Morgan's Raid. Large scale support for the Confederacy among Golden Circle members and Southern Hoosiers in general fell away after Morgan's Raid, when Confederate raiders ransacked many homes bearing the banners of the Golden Circle, despite their proclaimed support for the Confederates. When Hoosiers failed to rise in large numbers in support of the raid, Morton slowed his crackdown on Confederate sympathizers, theorizing that because they had failed to come to Morgan's aid in large numbers, they would similarly fail to come to the aid of a larger invasion.

One notable thing historians record from this period was the honesty with which the government was run. All of the borrowed money was accounted for with no graft or corruption and all was repaid in the years after the war. It was by these honest actions that Morton was able to avoid repercussions when the legislature finally was permitted to reconvene — this time with a new Republican majority.

In 1864 the war was nearing its end, though many saw no end in sight. The state constitution forbade a governor to serve more than four years in any eight year period, but Morton claimed that since he was elected as Lieutenant Governor and had only been completing Lane's term, he was eligible to run. The Democrats were furious again, and a bitter campaign was launched against Morton. Morton did not do a great deal of campaigning, but instead sought to have soldiers returned home to vote for him. Morton was reelected to office, defeating Democrat and longtime friend Joseph McDonald by over 20,000 votes. Although the campaign was conducted in time of war, with both parties strongly opposing the other, both Morton and McDonald remained friends after the campaign and later served together in the U.S. Senate. Many Democrats claimed that Morton had rigged the election because Republicans retook the majority in both houses of the Assembly.

Morton was partially crippled by a paralytic stroke in October 1865 which incapacitated him for a time. For treatment, Morton traveled to Europe where he sought the assistance of several specialists, but none were able to help his paralysis. During his recovery time Lieutenant Governor Conrad Baker served as acting governor. With the war ending, Baker oversaw the demobilization of most of the state's forces. Morton returned to the governorship in March 1866, but he was never again able to walk without assistance.

In 1867, Morton was elected by the General Assembly to serve as a United States Senator. He resigned from his Governor post that same year, again turning over the government to Lieutenant Governor Baker. In the Senate he first became a member of the foreign affairs committee and quickly grew to become a party leader. He was also made chairman of the Committee of Privileges and Elections. Because of his stroke, Morton always sat while delivering his speeches, but he was noted by other senators for his effectiveness in speaking and debating. Morton was in the Senate during Reconstruction and he supported most of the radical and repressive plans for punishing the southern states. Early in his first term in the Senate he supported legislation to eliminate all civil government in the southern states and impose a military government. He also supported legislation to void the southern states' constitutions and impose new ones. Among other things, he supported removing the right to vote from the majority of southerners and tripling the cotton tax. He supported the impeachment of President Andrew Johnson for his "moderate" views on reconstruction and openly voiced his disappointment when the impeachment failed. Although he had delivered a speech against giving blacks the right to vote in 1865, by 1870 Morton had completely changed his position and supported full suffrage for the former slave population. He is quoted as saying "I confess, and I do it without shame, that I have been educated by the great events of War." He championed the passage of the Fifteenth Amendment, and when the Democrats began to resign from the Senate during its debate to prevent quorum from being attained, Morton was the engineer of the maneuvering that kept the bill in the docket and allowed it to be passed.

After the new administration of President Ulysses S. Grant came to power in 1870, Morton was offered the position of Ambassador to Great Britain, but he refused. The Indiana General Assembly was controlled by the Democrats and he feared a Democrat would be elected to his seat. Morton was reelected to the Senate in 1873 and began his second term in 1874. Morton's stand on paper money made him controversial, he supported inflating the currency by printing money to pay down the war debt. He started the term by leading the Senate's support of the inflation bill that was vetoed by President Grant.

Morton was a contender for the 1876 Republican nomination for President at the Cincinnati Convention where his name was offered by Richard W. Thompson. His position on issuing paper money to inflate the currency, combined with his failing health, hurt him in his bid for the Republican presidential nomination among the convention delegates. His vote total placed him second to James G. Blaine on the early ballots. By the sixth ballot he had slipped to fourth place and on the next vote nearly all the anti-Blaine delegates, including Morton's, united to give Rutherford B. Hayes the nomination.

In 1877, Morton was named to lead a committee to investigate charges of bribery made against La Fayette Grover, a newly elected senator from Oregon. The committee spent eighteen days in Oregon holding hearings and investigations. On the return trip, Morton detoured to San Francisco, California, for a rest and visit. On the night of August 6, after eating dinner, he suffered a severe stroke that paralyzed the left side of his body. The next day he was taken by train to Cheyenne, Dakota Territory, where he was met by his brother-in-law John A. Burbank, the governor of the territory. Morton was accompanied by him to the home of his mother-in-law in Richmond, Indiana. He remained there to recover until October 15 when he was again moved to his own home in Indianapolis. He remained there, surrounded by his family, until his death on November 1, 1877.

Morton's remains were laid in state in the Indianapolis court house for three days after his death before being moved to Roberts Park Church where his funeral was held. His ceremony was attended by many dignitaries from across the United States. President Grant ordered all flags to half-staff. The church could not hold the crowd and the thousands of mourners waited outside and followed in a long procession to view the burial in Crown Hill Cemetery.

Morton gained many critics during his long tenure in government service. He was criticized and derided for the manner in which he ran Indiana during the Civil War. He openly suppressed freedom of speech, arrested and detained political enemies, and violated the state and federal constitution on numerous occasions. In the Senate he was one of the most radical reconstruction idealists, and pushed for numerous bills that, by design, had long ranging negative impacts on the development of the Southern United States. Despite holding many positions that angered his opponents, Morton was highly regarded for remaining clean of graft during the war period when corruption was commonplace. For his honest conduct he was offered the thanks of the Indiana General Assembly and others on numerous occasions. Morton succeeded in raising Indiana to national prominence during his lifetime. The state and its citizens were the common subject of jokes to the eastern states, but much of that ceased after the war.

Morton is memorialized in the United States Capitol as one of Indiana's two statues on the National Statuary Hall Collection. There are also two statues of him in downtown Indianapolis, in front of the Indiana Statehouse and as part of the Indiana Soldiers' and Sailors' Monument on Monument Circle. Another statue stands on the second floor of the Wayne County Courthouse in Richmond, Indiana, where a previous high school was named for him and the central section of the current high school is named Morton Hall in his honor. Morton Senior High School in Hammond, Indiana, home of the Morton Governors, is named after him, as is Morton County, Kansas. A statue of Governor Morton also serves as the State of Indiana's memorial at Vicksburg National Military Park in Vicksburg, Mississippi, in honor of his role as a powerful wartime governor.