This British Colonel Traveled with Robert E. Lee at Gettysburg. He’d Already Had His Share of Surprises

HistoryNet  

"Fremantle returned to England after having achieved the adventure he sought by his travel through Texas and by witnessing the Battle of Gettysburg. His account of his trip was published the ensuing year." 

"Arthur James Lyon Fremantle left Great Britain aboard a ship on March 2, 1863, headed for the northern border of Mexico. After a long voyage, the young British army officer finally arrived on April 1 “at the miserable village of Bagdad” on the Mexican side of the Rio Grande. Despite considerable speculation at the time, Fremantle was in America only as a tourist and not as an official governmental observer of the United Kingdom—the widespread uncertainty of his status undoubtedly caused by Fremantle’s choice of daily attire, a full British military uniform resplendent with a corresponding bright red jacket.

"Initially, Fremantle was inclined to side with the North in the Civil War, as were many of his fellow English citizens because of an inherent disapproval of slavery. He would soon switch his allegiance to the South, however, partly because he admired the Southern reputation of gallantry and determination, and also because “of the foolish bullying conduct of the Northerners.” As Fremantle would note: “I was unable to repress a strong wish to go to America and see something of this wonderful struggle.”

"As he attempted to cross onto Texas soil, Fremantle was briefly detained and questioned by a half-dozen Confederate officers. Ever the keen observer, the British citizen noted that the troopers—all from Colonel James Duff’s “Partisan Rangers,” the 33rd Texas Cavalry—were similarly attired in “flannel shirts, very ancient trousers, jack-boots with enormous spurs and black felt hats ornamented with the lone star of Texas.” Despite their unkempt appearance, the Texans treated Fremantle with inestimable kindness." . . .

Arthur Lyon Fremantle - Wikipedia  . . . "In the 1993 film adaptation of Shaara's novel, retitled Gettysburg, Lieutenant Colonel Fremantle is portrayed by James Lancaster

. His character changes little from the book, once again engaging in important discussions with General Longstreet and his officers on the Confederacy's relations with the United
Kingdom.^[49] However his appearance is substantially different from reality: in the movie he is shown in a scarlet British uniform sipping tea from a china cup, whereas, being in an unofficial capacity, he was dressed in a "gray shooting-jacket" and had been living rough like many others in the country." . . .