 Complete the following phrase:  Walkers rise to prominence was further accelerated by his appointment by Charles Francis Adams, Jr. as the Chief of the Bureau of Awards at the 1876 Centennial Exposition in Philadelphia. Previous world expositions in Europe were fraught with national factionalism and a superabundance of awards. Walker imposed a much leaner operation replacing juries with judges and being more selective in awarding prizes. Walker won formal international recognition when he was named a Knight Commander by Sweden and Norway and a Comendador by Spain. He was also invited to serve as Assistant Commissioner General for the 