Lipton's fourth challenge, the one he came closest to winning, was postponed six years because of World War I. But it seemed worth the wait.

    Armed with his Charles Nicholson-designed Shamrock IV, Lipton thought he had the Cup at last winning the first two races over the NYYC's Resolute. (Resolute did not finish the first race due to a breakdown.) However, because Shamrock IV was rated higher, a handicap (a ruling that cost her the Cup) was added to her time in the third race (a tie) and she lost by almost seven minutes.

    In the final two races, the Herreshoff-designed Resolute was not seriously challenged. Though Shamrock IV crossed the line first in three out of five races, the margin was never wide enough to offset the handicap penalty. The Cup remained at the NYYC.

    The aging Sir Thomas Lipton received a thrashing at the hands of another Vanderbilt, this time Harold S. "Mike" Vanderbilt, who became the first owner to sail his sailboat in America's Cup competition.

    Enterprise defeated the Nicholson-designed Shamrock V by as much as nine minutes.

    Designed by Starling Burgess (son of Edward Burgess), Enterprise is renowned for its "Park Avenue" boom, The large, flat boom, wide enough for a crewman to walk its length, allowed a curve to be put into the foot of the mainsail, thus achieving a more aerodynamic shape.     Shamrock V was restored 1999 by Pendennis Shipyard and is currently managed by J-Class Management.

    Sir T.O.M. Sopwith, the British aviation pioneer, turned his technological ingenuity toward the water, challenging with what has been judged as the superior sailboat, the Nicholson-designed Endeavor.

    Indeed, like Lipton's earlier series, Sopwith took a 2-0 lead over the NYYC's Rainbow in the best-of-seven match.

    But the 128-foot American sailboat Rainbow, designed by Edward Burgess' son, Starling, won the next four races—including Race 4, marred by a controversial luffing incident, and Race 5 (in which a crewman fell overboard) to win the series.

    Eneavour has been restored by yachtwoman Elizabeth Meyer.

    Sopwith returned in 1937 with Endeavor II, but she proved no match for Vanderbilt's Ranger, at 136-feet the largest "J" boat ever built.

    One of the most remarkable points of this defense was that it was the first of eight that involved the legendary Olin Stephens, of Sparkman & Stevens, as a designer (Ranger). It was Stephens who pioneered and refined the use of towing tanks in sailboat design.