I've read a bit about the tactical transition from pike based armies with arquebus support to mostly gunpowder armies. What nation(s) developed that and did it make an immediate impact on their success? What time frame are we looking at? Thank you!
Ottoman Janissaries had fully embraced firearms by the early 16th century, and this contributed to the Ottoman expansion during that time. Perhaps this is best exemplified by the Battle of Mohacs in 1526, where skilled Ottoman musketeers annihilated the traditional Hungarian Knights.
Are you asking about the first use of firearms, the first use of pike and shot, or the process of moving from pike and shot to pure shot?