In , Rolex agreed to acquire its longtime retail partner Bucherer , [ 11 ] [ 12 ] and in , Rolex began construction of a new headquarters on Fifth Avenue in Midtown Manhattan , New York City , near Billionaires' Row. These early wristwatches were sold to many jewellers, who then put their own names on the dial. In , Wilsdorf registered the trademark "Rolex", which became the brand name of watches from Wilsdorf and Davis.
He opened an office in La Chaux-de-Fonds , Switzerland. During World War I , Rolex manufactured trench watches. With administrative worries attended to, Wilsdorf turned the company's attention to a marketing challenge: the infiltration of dust and moisture under the dial and crown, which damaged the movement. To address this problem, in a third-party casemaker produced a waterproof and dustproof wristwatch for Rolex, giving it the name "Oyster".
The original patent attributed to Paul Perregaux and Georges Peret, that allowed the watch to be adjusted while maintaining protection from water ingress was purchased by Rolex and heavily marketed. As a demonstration, Rolex submerged Oyster models in aquariums , which it displayed in the windows of its main points of sale.
In , British swimmer Mercedes Gleitze swam the English Channel with an Oyster on her necklace, becoming the first Rolex ambassador. To celebrate the feat, Rolex published a full-page advertisement on the front page of the Daily Mail for every issue for a whole month proclaiming the watch's success during the ten-hour-plus swim.
In , Rolex patented a self-winding mechanism called a Perpetual rotor, a semi-circular plate that relies on gravity to move freely. In turn, the Oyster watch became known as the Oyster Perpetual. Upon the death of his wife in , Wilsdorf established the Hans Wilsdorf Foundation , a private trust, in which he left all of his Rolex shares, ensuring that some of the company's income would go to charity.
