Abraham Lincoln was mad. Really mad.

"How, in God's name, do you let such paragraphs into the Tribune?" he furiously scribbled in Springfield on June 27, 1858, firing off a gruff note to Charles H. Ray, the editor-in-chief of the Chicago Press & Tribune, then in business for only 11 years.

"Does Sheahan write them?" Lincoln sneered, a sarcastic reference to James Sheahan, editor of the Chicago Times, a Democratic Party paper and the Tribune's chief rival.

"I confess," Lincoln wrote, the consternation dripping, "it astonishes me."

It wasn't the first time Lincoln had fumed at what he read in the Tribune. A few weeks earlier he'd written a longer letter, reprimanding Ray for "a great injustice" the Tribune had done his friend, George Davis, in its coverage of Davis' opposition to Rep. Owen Lovejoy, another Republican.

"I wrote this chiefly ... to express my regret that articles like the enclosed should appear in our own Republican papers, planting poisonous thorns to rankle in the bosoms of our own best men."

The letters are part of a set of five held at the Col. Robert R. McCormick Research Center at Cantigny Park, the former home of legendary Tribune publisher and philanthropist Robert McCormick. Discussions are ongoing to move the letters (which can be read below), along with a trove of correspondence from McCormick and other Tribune leaders, to a new home at Northwestern University. The archives include communications with nine U.S. presidents and Winston Churchill, according to Cantigny.

"I wrote this chiefly ... to express my regret that articles like the enclosed should appear in our own Republican papers, planting poisonous thorns to rankle in the bosoms of our own best men." —Abraham Lincoln, in a letter dated June 6, 1858

While not newly discovered, the Lincoln correspondence is relatively little known, according to historians. These private writings, all sent before he was president, catch Lincoln in a far different light from how he's often profiled.

Lincoln scholar and Dickinson College professor Dr. Matthew Pinsker describes the June 27 letter to the Tribune as "the angriest, nastiest written statement Lincoln ever produced (at least as far as we know)."

In an era when newspapers were far from politically neutral, reporting and editorials were seen as a natural extension of political movements. And a pre-presidential Lincoln, apparently, was quick to anger at Republican newspapermen he felt worked against his interest and the interest of his nascent party.

He routinely refers to the Tribune's leadership as "we," and clearly carries the expectation the paper play for the Republican team, which had been established only a few years before to oppose slavery's westward expansion. It already had largely replaced the former Whig Party in the northern states, but wasn't yet the dominant force it became after Lincoln.

In one letter, Lincoln coordinates part of his presidential campaign with Tribune managing editor Joseph Medill, McCormick's grandfather and later Chicago's mayor. Lincoln shares campaign dispatches from the field with Medill, who had written to Lincoln with his own intelligence. In another, Lincoln provides a detailed account of his voting record to Medill in order to refute a Chicago Times piece that falsely accused him of failing to provide for soldiers in the Mexican-American War during his single term in the U.S. House, from 1847 to 1849.

In his June 6 letter, Lincoln says he was perturbed the Tribune had lumped his friend Davis in with a group of "bolters" who worked against Lovejoy two years before because he was viewed as too radical an abolitionist for the young Republicans. The party officially only sought to cease slavery's expansion. (Lovejoy was the brother of prominent Illinois abolitionist publisher Elijah Lovejoy, who was killed by a pro-slavery mob that destroyed his printing press in Alton in 1837.)

Lovejoy won that race and would represent Illinois in the House as an ardent opponent of slavery until his death in 1864.

In his far angrier June 27 letter, Lincoln is enraged the paper had allowed a column that encouraged Republicans to vote for an independent Democrat for Congress in Indiana (over his "doughface" opponent) because of the Democrat's opposition to a constitution for Kansas that protected slavery.

Lincoln would have been "absolutely furious" over the idea appearing in his Republican Tribune, according to Dr. Christian McWhirter, a historian at the Abraham Lincoln Presidential Library and Museum in Springfield. His famed Democratic rival, Stephen A. Douglas, had also broken with his party against what was known as the Lecompton Constitution. As Lincoln figured it, if it were all right for Republicans to vote for incumbent Democrats who opposed the pro-slavery constitution in Indiana, might they vote for the incumbent Douglas — and not him — in the 1858 election in Illinois?

Slavery was one of the biggest issues in that contest, famously dominating the Lincoln-Douglas debates across Illinois. Muddling the distinction between Democrats who opposed a pro-slavery constitution in Kansas — but supported slavery where it had popular support — and anti-slavery Republicans would have been a political sin in Lincoln's eyes.

And while publicly calling for Republican loyalty, he took a dig at fellow party members in his private letter, questioning the manhood of Massachusetts Republican Anson Burlingame, who he labeled "Sister Burlingame."

In addition to being a sender of angry letters, Lincoln also was known to burn personal correspondence and instruct recipients of his letters to do the same, according to Pinsker. For all we know, the most vitriol-laced or embarrassing notes might have gone up the flue more than a century ago.

And yet, for all the heat Lincoln gave Ray in the summer of 1858, the letters also make clear he loved the Tribune and saw it as invaluable to his cause and presidential campaign. That might explain why he seemed so hurt, even personally aggrieved, by writing he viewed as damaging. It was more sibling squabble than blood feud.

A year later, in June 1859, he sent a dispatch from Springfield to Chicago to enclose his yearly subscription fee. He wrote, "I suppose I shall take the Press & Tribune as long as it, and I both live ... In its devotion to our cause always, and to me personally, last year (during his failed campaign against Douglas), I owe it a debt of gratitude, which I fear I shall never be able to pay. Yours very truly, A. Lincoln."

Meaningful correspondence continued long after Lincoln went on to occupy the White House. Medill wrote a letter to Lincoln after the war, saying the paper will "back him up stoutly," but cautioned him to rethink a lenient course of Reconstruction. In the letter, also held at Cantigny, Medill encouraged the president to hang some Confederate leaders, ban others from holding office or military commissions and cautioned him not to "deal too leniently with the cruel, vindictive villains who starved to death with devilish malice 25,000 of our brave patriotic sons and brothers."

"There can be no forgiveness for them on this side of the grave," Medill wrote.

Lincoln never had a chance to consider the Tribune editor's advice. That letter is dated April 14, 1865 — the day he was shot in the head at Ford's Theatre.

charjohnson@chicagotribune.com

Twitter @Charliemagne