As you know banners, in the Bible standards or flags were set up to distinguish tribes. There is no record of ‘pledges’, but they were used during battle to give troops encouragement and a focal point.
Numbers 1:52 (NKJV)
52 The children of Israel shall pitch their tents, everyone by his own camp, everyone by his own standard, according to their armies;
When God is our victory banner (Yehovah Nissi) He is our encouragement and focal point from one victory to another.
Psalm 20:5 (NKJV)
5 We will rejoice in your salvation,
And in the name of our God we will set up our banners!
May the Lord fulfill all your petitions.
Thus, our allegiance isn’t to a piece of cloth (which can become an idol), but to our God, our Elohim, the Father of our Savior Yeshua the Messiah, Jesus Christ.
After God gave Moses victory over the Amelakites he built an alter and called it , Yehovah Nissi (The Lord is my Banner).
Exodus 17:15 (NJKV)
And Moses built an altar and called its name, [a]The-Lord-Is-My-Banner;
Whenever you need encouragement, or to rally people together for a Godly cause, call on the symbolic name of God that specifically refers to that aspect of His character…and always let your first allegiance be to Him.