I think the Chargers were a LA expansion team when they started,
You are correct. They were the Los Angeles Chargers in their first, 1960.
Oops, I meant to say that they were a charter team in the newly created American Football League, and were in LA for only their first year, 1960.
Barron Hilton, son of the great hotelier Conrad Hilton, was the first owner.
In 1960, Kemp led the Chargers to a Western Division Championship with a 104 record. He finished second in the league to Frank Tripucka in passing attempts, completions, and yards (making him and Tripucka the league's first 3,000-yard passers), led the AFL in yards per completion and times sacked, and finished one rushing touchdown short of the league lead. Under Kemp, the Chargers' offense averaged 46 points over its last four games and scored more than 41 points in five of its last nine games. In the 1960 AFL Championship Game, he led the team to field goals on its first two possessions, but after the Houston Oilers posted a touchdown in the second quarter for a 76 lead, the Chargers never recovered. (h/t Wikipedia)
I remember watching that first AFL Championship game as a kid. My favorite player (for either team) was Houston's Charlie ("The Human Bowling Ball") Tolar.