General Richard Meyers threw out the first pitch to injured Royals third baseman Mike Moustakas.
After the National Anthem was sung, a military flyover drew loud cheers.
The names of fallen soldiers from Missouri and Kansas were listed on the stadium scoreboard, after a moment of silence.
And the families of Cpl. Benjamin Ashley and SFC Gary Collins, both of whom died in action, were honored with a special ceremony at home plate, complete with a video tribute. Royals players Luke Hochevar, Eric Hosmer and Moustakas presented the families with flowers.
Jeffrey Flanagan has covered the Royals since 1991, and for MLB.com since 2015. Follow him on Twitter @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.