10 Cents Military Payment Certificate

Series 641, issued from 1965, was replaced mid-Vietnam War by Series 651 in 1968 — this note belongs to that replacement cycle. MPC conversions were conducted as surprise "C-Day" events: a single day's notice, after which old series became worthless. The purpose was to freeze out black market operators and Vietnamese civilians who had accumulated dollars-adjacent currency outside sanctioned channels.

Series 651 had a notably short run, replaced again by Series 661 in 1969. That brevity makes surviving examples more interesting to track than the longer-running series.