How does Sherriff create tension in the duologue between Osborne and Stanhope at the end of Act 1?

Stanhope meets the revelation that Raleigh has joined his company with unease. The presence of Raleigh introduces a new conflict to the play that involves the themes of heroism, alcoholism, and PTSD (post-traumatic stress disorder). Stanhope knows that Raleigh’s sister to whom he is engaged believes he is a hero, but now he worries that Raleigh’s sister will learn of his true state: traumatized by the war and needing to soothe his nerves by remaining constantly intoxicated.

The theme of PTSD continues with Hibbert’s complaints of neuralgia, an intense and intermittent pain in the head. Stanhope is suspicious that Hibbert is faking his illness in order to be sent to the hospital before the big attack comes, comparing Hibbert to a lowly wriggling worm.