Jackson was born on August 19, 1862, in Newark, New Jersey, the son of Frederick Wolcott and Nannie (Nye) Jackson. Although his father, grandfather, and great-grandfather had been identified with the railroad interests of New Jersey, John early decided upon a naval career.
Jackson was graduated from the United States Naval Academy in 1883 and spent the next two years with the European Squadron. Shortly after his marriage he was ordered to join the Pacific Squadron but because of his wife's ill health, resigned his commission as ensign, June 30, 1886. He then began the study of law and was admitted to the New York bar in 1889.
On December 30, 1890, President Harrison appointed Jackson second secretary of the legation in Germany, then in charge of Minister Phelps of New Jersey. Four years later President Cleveland commissioned him secretary of embassy, in which capacity, frequently as chargé d'affaires ad interim, he served at Berlin until 1902. His twelve years in Germany under four administrations gave the American mission a valuable continuity when both countries were embarking as world powers, and when the new Emperor's aggressive political and commercial policies in the East and in the West were coming into conflict with those of the United States. Jackson was in charge of the embassy in all about twenty months, including the last tense month of the Spanish-American War, during the Hague Conference of 1899, and while the Boxer Rebellion in China was at its height. Jackson was personally respected and liked by the Emperor and by German officials generally and he held the confidence of the chiefs of mission under whom he served. His loyal and efficient services in Germany won him a commission of October 13, 1902, as minister to Greece, in which capacity he served until 1907. During this period he was accredited, at various times, to Romania, Serbia, Bulgaria, and Montenegro. He then spent two years each as minister to Persia and Cuba, returning to the Balkans in 1911 as minister to Romania, Serbia, and Bulgaria. His long experience in Europe made his early services as minister of great value but gradually Jackson became less successful in maintaining the confidence of his government. According to custom, he submitted his resignation with the coming of the Democratic administration. It was accepted in August 1913, and he left Bucharest two months later. Upon the outbreak of the World War he volunteered his services to the American embassy at Berlin. On January 16, 1915, he was made a special agent of the Department of State to assist the ambassador in matters relating to the war. Because of previous experience in Germany his services proved invaluable and he was retained on the embassy staff until its withdrawal in February 1917. Thereafter Jackson remained in Switzerland, where he died after a prolonged illness at the early age of fifty-eight.
Jackson married Florence A. Baird of Philadelphia, on April 26, 1886.
