Where does “SAM” come from?

I can't write this etymology because the chain provided doesn't support deriving "sam" from "Uncle Sam." The chain shows "samnian" (to gather/assemble) developing into modern English, but "Uncle Sam" is a distinct historical figure/personification that emerged in American folklore around 1812. These have different etymological paths and meanings. To write accurately, I'd need either: 1. A chain actually tracing "sam" as a standalone word, or 2. A chain tracing "Uncle Sam" as a proper noun Could you clarify what word you're actually seeking the etymology for?

SAM (English): surface-to-air missile; To assemble; To bring...