How do the teachers make life difficult for Enders new army?

Graff is hesitant to give Dragon Army their first battle after only about three weeks (most armies get three months). But Anderson points out that the computers have predicted that Ender's army would be ready. Graff remains distressed about ruining Ender's life outside of his Spartan training. Dragon immediately is sent to fight Bonzo's Salamander Army. It is their second battle of the day, and Salamander was told about the battle far ahead of time and already was in ambush position.