Hartshorne, from a Quaker family which had established itself in New Jersey, came up with the loyalists when the final evacuation of New York by the British forces occurred in 1783. He became a hardware dealer at Halifax in partnership with Thomas Boggs, a fellow refugee from New Jersey.
Hartshorne's chances of making his way up the social ladder, as with so many loyalists who came to Nova Scotia, were greatly increased when John Wentworth was named the Lieutenant-Governor of Nova Scotia in 1792. Indeed, it has been suggested1 that it was this connection to Wentworth which helped Hartshorne to win, by election, a seat in the House of Assembly for Halifax County in 1793. He was defeated in the general election of 1799 by one of the reformers under the leadership of Tonge. But then, as it seems yet today, a defeat of a person loyal to the headman, in this case Wentworth, meant a cushy appointment in the governmental setup; for Hartshorne it was a seat on the ruling Council.
In and around 1792, Hartshorne formed a partnership with Richard Tremain. The pair were responsible for building a combined grist-mill and bakehouse at Dartmouth, across the harbour from Halifax. His partnership with Boggs continued and indeed flourished when war came once again in 1793. Hartshorne continued to nurture his relationship with the governor, including, loaning "money to the frequently hard pressed Wentworth family."2 Though it is clear that Hartshorne's good fortune in business was brought on by his connection to the Wentworths, even when Wentworth was suddenly replaced by Prevost, Hartshorne continued to be in the good graces of government; and, often when special inquiries were to be made, such as whether the province should issue paper money (1812), Hartshorne was consulted. Hartshorne was married before he came to Nova Scotia. He married a second time in 1802, to Abigail Tremain, the daughter of his business partner. There were children from both of his marriages, a family of three sons and six daughters.