What event is credited with the adoption of the logo "the open eye" and the slogan "We Never Sleep" by the Pinkerton Agency?

Around 1850 he formed Pinkerton's National Detective Agency, with the motto "We Never Sleep" and an unblinking eye as its symbol. This would lead to the description of independent detectives as "private eyes."

Among the business's early operations was to safely deliver the newly elected President of the United States, Abraham Lincoln, to Washington, D.C., in light of an assassination threat. Pinkerton detective Kate Warne was assigned and successfully delivered Lincoln to the U.S. capital city through a series of disguises and related tactics that required her to stay awake throughout the entire long journey. As a result of the public notoriety of this success, the business adopted an open eye as its logo and the slogan, "We never sleep."