The document dated March 8, 1796, was signed by the future Napoleon I and his fiancee Marie Josephe Rose Tascher de La Pagerie, or Josephine, the Viscomtesse de Beauharnais.
The wedding itself took place the next day, and the contract was registered in Paris on March 18.
Despite history recording their passionate love affair, the document shows that the star-crossed lovers could also be very practical.
The document is expected to fetch up to 100,000 euros (USD135,000) when it is auctioned on September 21 by Maison Osenat, at a sale in a suburb west of Paris.
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The auction, which will feature a number of other manuscripts and items from the era, will also feature two documents related to Bonaparte's arrest in 1794.
At a previous auction in 2007, a love letter to Josephine written before they were married, sold for more than five times the pre-sale estimate.
The marriage was annulled in 1810, after the couple failed to have children.