Some do not believe that Abey Lincoln traveled to Washington, DC, in 1861, disguised in a Scotch cap and cloak. This was asserted by Mrs. Rose O’Neal Greenhow, Confederate spy.
Mrs. Rose O’Neal Greenhow (ca. 1813 – 1864) viewed with alarm the rise of the Yankee abolition government. Ensconced in the federal city of Washington, the charming southern belle played a key role in the Civil War — that of a Rebel spy!
In her book, My Imprisonment and the First Year of Abolition Rule at Washington, Mrs. Greenhow provides key insights on the Yankee government.
Early on, the coy charmer alludes to the incident of “the Scotch cap and cloak” and to the advent of the “Irrepressible conflict chief.” He “had been elected President by a strictly sectional majority…” Abey Lincoln snuck into town disguised in a Scotch cap and cloak. He then announced his presence with, “Hillo! Just look at me! By jingo, my own dad wouldn’t know me!” 
James Mackay’s acclaimed biography of Allan Pinkerton confirms that indeed Lincoln snuck out of Harrisburg, Pennsylvania disguised in a Scotch cap and cloak, and arrived in West Philadelphia wearing same. 
“The Republican Party in its early days was the new broom in American politics, opposed to slavery even if not openly committed to abolitionism, and containing many radical elements whose left-wing views were pretty much in line with Allan’s [Pinkerton’s] own outlook. Not until very much later did it become a more right-wing party, with a strong reactionary fringe.” 
Allan Pinkerton’s avant-garde detective agency was chosen to protect “radical” president-elect Abraham Lincoln against dangers besetting him as he journeyed to Washington, DC in 1861.
“In February 1861, George Sanders, ‘La Marseillaise’ singer with James Buchanan, Giuseppe Mazzini, Felice Orsini, and others, just happened to be in Cincinnati, Ohio. Sanders was in Cincinnati to contact members of the Knights of the Golden Circle (KGC), which then had its headquarters in that city.” 
“On February 12, 1861 (Lincoln’s birthday anniversary), in Cincinnati, coincident to the presence of George Sanders, a carpet bag containing a ticking time bomb was placed onboard Lincoln’s train. Luckily, an alert attendant heard the ticking and informed Lincoln’s security men.” 
The Felice Orsini mentioned above is connected to one Cypriano Ferrandini. Ferrandini was recently-arrived in America. A few years earlier, Ferrandini “had been implicated in the [Felice] Orsini plot to assassinate Napoleon III and had narrowly escaped the guillotine.” Allan Pinkerton, disguised as “J.H. Hutcheson” of Charleston, snooped upon Cypriano Ferrandini. Even the tough-as-nails Pinkerton felt himself as if hypnotized by the influence of Ferrandini’s “strange power.” 
After his narrow escape in Cincinnati, Lincoln and his entourage continued on, in a meandering way, to Washington, DC. “On February 16, 1861, Lincoln’s train arrived in Buffalo, New York. There the president-elect was greeted and entertained by Millard Fillmore. (‘at vero Melchisedech rex Salem proferens panem et vinum…‘) It was ‘a cordial weekend.’ Our Millard ‘entertained Lincoln at his home and paid him every attention…’ It seems likely that Millard Fillmore would have conferred privately with Mr. Lincoln regarding urgent national matters.” 
On February 19, 1861, the president-elect and his group were in New York City. The previous evening, one Kate Warne, the first female private detective, had arrived from Baltimore. Kate Warne had been hired by Pinkerton and was working to protect Lincoln. A letter in the trusting of Kate Warne alarmed the Pinkerton group. It was considered that Lincoln’s running mate, Hannibal Hamlin, ought to be consulted. But Kate Warne “emphasised that no one could be trusted and that the only man who should be told was Lincoln himself…” 
“Allan Pinkerton named Kate Warne one of the five best detectives that he had. Her convincing Pinkerton to employ her was a significant moment in woman’s history. Women were not allowed to be a part of the police force until 1891 and could not be detectives until 1903.” 
Eventually, Lincoln was persuaded that a “Baltimore Plot” was afoot. Allan Pinkerton had become convinced that a conspiracy existed to ambush Lincoln’s carriage between the Calvert Street Station of the Northern Central and the Camden Street Station of the Baltimore and Ohio Railroad. This opportunity would present itself during the President-elect’s passage through Baltimore on February 23, 1861. On the evening of February 22nd, telegraph lines to Baltimore were cut to prevent communications from passing between potential conspirators in Pennsylvania and Maryland. Meanwhile, Lincoln left Harrisburg on a special train and arrived secretly in Baltimore in the middle of the night.
In Harrisburg, Abey Lincoln had put on a special disguise, “a long, threadbare military cloak and with a Tam o’ Shanter woolen cap [Scotch cap] on his head.” Lincoln was thereby transformed into a “strange figure” in a “shabby cloak and Scotch bonnet.” 
(A version of the above first appeared at my Melchizedek Communique web site on May 8th and May 9th, 2011.)
——- Sources ——-
 Greenhow, Rose. My Imprisonment and the First Year of Abolition Rule at Washington. London: Richard Bentley (publisher), 1863
 Mackay, James. Allan Pinkerton: The First Private Eye. Wiley & Sons, 1997
 Redman, Brian. What Would Millard Do?. 2009. Published by Lulu.com. Also available as a Kindle e-book
 “Kate Warne”, Wikipedia, May 8, 2011