 Jachmann was born in Danzig on 2 March 1822, the youngest of seven children, to Dr. R. H. Jachmann and Minna Jachmann (née Schaff).Eduard attended grammar school in Marienwerder.Against his father's wishes, Jachmann joined the merchant marine as a cabin boy in Danzig in 1839; at the time, it was uncommon for an educated young man to join the shipping industry.