Overview
St. Helena (also known as Napoleon's Favourite or Washington's Favorite) is a patience or card solitaire game using two decks of playing cards shuffled together. Despite its name, it has no connection to the island with the same name, nor should it be confused with the better known Napoleon at St Helena, also called Forty Thieves in the US.
Rules
Explained here is the prevalent version. First, one king and one ace of each suit are removed and place in the middle of the table in two rows as shown. They are called the bases for the foundations. The kings form the upper foundations, while the aces form the lower foundations. Then, the rest of the cards are dealt clockwise into twelve piles starting with the upper left king. The table should now look like this:
The object is to build the upper foundations down by suit to the aces, and the lower foundations up by suit.
From Wikipedia (CC BY-SA 4.0).