From 1781 to 1789 how did the articles of confederation provid the united states with an effective government.

I would say the Articles of Confederation provided the United States with a government that was effective enough to keep the country functioning in the short term, but not one that was effective enough to last in the long term.

in 1897, pershing became a tactical officer at west point, and that's where he was given the nickname "black jack." pershing's first name is "john," for which "jack" is a nickname, and he was a white man who commanded black troops. hence "black jack".