Jacob Crowninshield, brother of Benjamin Williams Crowninshield, was born in Salem, Massachusetts, in 1770. He began his professional career in the field of commercial shipping, working as ship's captain and merchant for his father's merchandising firm, George Crowninshield & Sons. Jacob left the private sector to enter public service in 1801, when he gained a seat in the Massachusetts State Senate. Crowninshield moved on to Washington, D.C., in 1803, joining Congress as a representative from Massachusetts. In 1805, President Thomas Jefferson offered Crowninshield a position as secretary of the Navy following former secretary Robert Smith's request to transfer from that post to the office of attorney general; he was quickly confirmed by the Senate. However, Crowninshield never took office, reneging on his commitment due to poor health. Instead, he continued his political career, remaining a congressman until his death, while in office, in 1808.