History tends to focus on the failures of the Articles of Confederation in early America, which caused the Constitution to eventually be written to replace them.
However, they still were in place and governed for around 10 years, which is still pretty impressive considering the size of the United States as well.
So something had to have been done right during that time...what were the successes of the Articles of Confederation during the very beginning of the United States?
I think the best example of a success of the Article of Confederation (that is, the government of the first American republic) was the Northwest Ordinance (1787). It organized the Northwest Territory (basically all land north of the Ohio River, east of the Mississippi, and west of the Appalachian Mountains), set the standard by which America expanded westward, and organized the process by which new states were admitted to the Union (notably, old states wouldn't assume new lands). It also had existing states renounce their claims to the new lands and they entered US public domain. Additionally, it prohibited slavery in the new territories, establishing the Ohio River as a somewhat boundary for the expansion of slavery in the US. It also accomplished other things, like establishing a public university in the new territory, establishing some form of natural rights (which influenced the Bill of Rights potentially), and influenced future relations with Native Americans in the area.