Read the passage.
(1) most americans know that “uncle sam” is a nickname for the united states; however, few americans know how the name originated. (2) some historians believe the name comes from a nineteenth-century businessman from new york. (3) his real name was samuel wilson. (4) his neighbors called him uncle sam. (5) during the war of 1812, he won a government contract. (6) he was to supply beef to u. s. soldiers. (7) the beef was packed in barrels labeled “u. s.” to show that they belonged to the u. s. government. (8) soldiers from new york saw the barrels. (9) they jokingly said “u. s.” stood for uncle sam. (10) the joke spread. (11) soon, soldiers began using the nickname uncle sam to refer to the united states. (12) civilians also began using the nickname uncle sam to refer to the united states. (13) in 1961, congress passed a resolution. (14) the resolution recognized samuel wilson as the original uncle sam.
which is the most effective way to combine sentences (5) and (6)?

during the war of 1812, he won a government contract he was to supply beef to u. s. soldiers.

during the war of 1812, to supply beef to u. s. soldiers was what he won a government contract for.

during the war of 1812, he won a government contract to supply beef to u. s. soldiers.