[2] Family tradition holds that Jacob Hägg decided to become a naval officer after seeing the French-British expeditionary force sail past Gotland on its way to the Battle of Bomarsund during the Crimean War in the summer of 1854.
In 1864–1865 he sailed with the steam corvette Gefle (1847) [sv] to the Mediterranean and the west coast of Africa; a travelogue from this journey was later published, to which Hägg contributed the illustrations.
[2] He later also sailed on several long journeys, including one circumnavigation of Earth, with the steam frigate Vanadis (1862) [sv], which he was the commander of the years 1890–1894, and on the corvette Saga.
Hägg was at that point accused, wrongfully as it turned out, to have broken a vow of silence regarding upcoming promotions of naval officers.
[8] Hägg himself refrained from engaging in the debate, apart from a single attempt to downplay the incident in an article in Post- och Inrikes Tidningar.
He was largely self-taught; apart from being taught basic drawing in school by Pehr Arvid Säve and later attending a course in oil painting by Per Daniel Holm, he had no formal education in the arts.
Initially he had trouble finding a studio he could use, and while serving as commander of Vanadis in the 1890s, he used the great cabin as an atelier for his oil painting.
[11][12] Stylistically, he can be counted among the juste milieu painters; the ambience or atmosphere is often romantically portrayed, while his great technical skill and nautical knowledge contributes to a high degree of realism in the depiction of ships and other subject matter.
[13] When he came to Stockholm as a young man, he found inspiration among the collections of Nationalmuseum; in particular the art of Johan Fredrik Höckert influenced him.
[2] The Swedish Maritime Administration operates a hydrographic survey vessel named R/V Jacob Hägg [sv].