He was born Arvid Bernhard Horn of Kankas in Vuorentaka, Finland, the son of GustafHorn of Kankas och and his wife Anna Helena von Gertten.
After the death of Charles XII, in 1718 it was Horn who persuaded the princess Ulrika Eleonora of Sweden to relinquish her hereditary claims and submit to be elected queen of Sweden.
He was elected lantmarskalk, for the Caps at the Riksdag of 1720, and contributed, on the resignation of Ulrika Eleonora, to the election of Frederick of Hesse as king of Sweden, whose first act was to restore to him to the Privy Council and as President of its Chancellery, in effect as Prime Minister.
CARL GUSTAF TESSIN, Count (1695-1770), Swedish statesman, son of a great architect, Nicodemus Tessin, began his public career in 1723, at which time he was a member of the Holstein faction.
In 1725 he was appointed ambassador at Vienna, and in that capacity counteracted the plans of the Swedish chancellor, Count Arvid Horn, who was for acceding to the Hanoverian Alliance.
On the division of the spoil of patronage he chose for himself the post of ambassador extraordinary at Paris, and from 1739 to 1742 delighted Versailles with his brilliant qualities of grand seigneur, at the same time renewing the traditional alliance between France and Sweden which had been interrupted for more than sixty years.