Not long after LCpl. Blake
Saves LCpl. Schofield from a collapsing German bunker
He and Schofield get into an argument about continuing on with their perilous journey. It's obvious Schofield is upset about being picked for their dangerous mission to which Blake responds with something like "If you don't like it, you can always go back."
Schofield simply retorts "Just fire the bloody flare" and Blake obliges.
Why did Blake fire his flare gun and subsequently drop it?
Earlier in the movie when the two were given the flare gun they were instructed to "throw it back" if they found themselves under fire as it was a useful piece of equipment and the British troops didn't want to leave it on a corpse.
Were they requesting reinforcements now that they had advanced as far as they had? Was it a signal of distress? If that were the case why did Schofield move onward with Blake?