I want to know the answer to the following question:
WHo reformed the grand duchy army?
All the background I'm provided with is that "In the late 14th century, in the Grand Duchy of Lithuania, Vytautas the Great reformed the Grand Duchy's army: instead of calling all men to arms, he created forces comprising professional warriors—bajorai ("nobles"; see the cognate "boyar").". Is that enough to answer the question?
Answer: yes