Given the state of aviation technology in the early decades of the 20th century, a flight of 1,100 miles across the Atlantic ocean would be like a trip to the moon today. World War I saw some advances in the aviation front by Europe, but nothing that was remotely capable of completing a transoceanic flight. The dream lived on, however, nurtured from 1913, when Alfred, Lord Northcliffe, publisher of the London Daily Mail newspaper, announced a prize of £10,000 ($25,000) to the first transatlantic flight. Northcliffe’s rules specified planes could land on the water along the way, and be refueled in the Azores islands, as long as the flight resumed from the point of touch down. The only plane capable of making that flight would have to be a seaplane, and the best seaplanes were manufactured by Glenn Curtiss.

On this day, May 27, the first plane to cross the Atlantic ocean, a Curtiss NC-4, landed triumphantly at Lisbon, Portugal, completing the last leg of a flight that took off in New York nineteen days before.

The NC-4 was one of three planes sent on the journey, together with the NC-1 and the NC-3 (the NC-2 was dismantled for parts for the others). The NC-1 and 3 initially jumped out ahead, while the 4 was delayed almost right away with technical troubles, but in the middle of the course both planes had to set down on the rough seas, which precluded them from taking off again. The NC-4, despite a fog thick enough to hide the crew from each other, found by radio transmission and dead reckoning their flight path, and completed their journey without falling into the trap of the other two.