To quote Wikipedia: "Aimé Félix Tschiffely (May 7, 1895 – January 5, 1954) was a Swiss-born, Argentine professor, writer, and adventurer. A.F. Tschiffely (as he was better known) wrote a number of books, most famously Tschiffely's Ride (1933) in which he recounts his solo journey on horseback from Argentina to Washington DC, an epic adventure that still marks one of the greatest horse rides of all time. Tschiffely was a household name in the United States during the 1930s, meeting with President Calvin Coolidge and appearing in National Geographic Magazine and earning a lucrative living from his popular book sales."
While in London after WWII, a Spanish professor convinced him to explore Spain. However, the British government did not allow anyone to leave with more than 50 pounds in currency due to post-war restrictions. That ruled out Tschiffely having enough money to buy a horse in Spain. Royal Enfield stepped up and donated a Royal Enfield R.E. 125cc motorcycle. He rode for 5000 miles and wrote a book "Round and About Spain"
In addition to that they used Tschiffely's abilities learned in the Pampas for promotional purposes. Here we see him lassoing Graham Walker, editor of "Motor Cycling" while riding a Royal Enfield. This clearly speaks to the publicity genius of Royal Enfield. Could we imagine today, say, Honda Motors having an editor of Cycle World lassoed as a promo?