The Entrance is, more or less, Da pacem Domine, which is used for the 24th Sunday in OT (formerly, 18th Sunday after Pentecost). The corresponding Offertory is Sanctificavit Moyses. However, Da pacem is also used in the 1962 Missal as a votive Mass for peace (always appropriate for a national holiday), with the Offertory Laudate Dominum quia benignus est (4th Sunday of Lent in the modern Missal), which might be a better choice. I attach my version, but you can find others.
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