Career
After studies at the gymnasium in Odense he entered the Danish army as subaltern in 1864 and fought in the Danish-German war. At the end of 1864 he joined the Imperial Mexican Volunteer Corps de:Österreichisches Freiwilligenkorps in Mexiko and fell into captivity of the Mexican Republicans at the end of the month-long siege of Oaxaca. He was freed in 1867, rejoined the Danish army as lieutenant and had himself posted in the Danish Antilles, where he served until his retirement, as captain, in 1885.
His retirement from the army marked the beginning of his career as botanist.
He studied and published the flora of Saint Croix, Saint John, Saint Thomas, Water Island and Vieques. He made numerous trips and collected extensively on virtually all the islands of the Greater and Lesser Antilles: Dominica in 1880, Puerto Rico in 1881 and 1883, Tortola, Saint Kitts, the Dominican Republic and Turks in 1887, Haiti, Jamaica and the Bahamas in 1888-1889 and Tobago, Trinidad, Grenada, Saint Vincent and Barbados in 1889-1890.
He moved to Ecuador in 1891 where he stayed until 1897 making numerous collections. He had a hacienda at El Recreo, in the vicinity of San Vicente in Manabí province.
The genus Eggersia, was named for him by Joseph Dalton Hooker.
The species Eggersia buxifolia (Hookf) is synonymous with Neea buxifolia (Hookf) Heimerl. Strumigenys eggersi - Eggers" dacetine ant
Agave eggersiana - Saint Croix Century Plant
Erythrina eggersii.