Septimus is a shell-shocked World War I soldier. He’s a unique figure in literature because he was one of the first characters to show the horrors of war and the trauma that occurs after combat. Woolf doesn’t depict him as a hero, but rather as a sufferer and survivor – another sort of casualty of war. Septimus is plagued by feelings of numbness, hallucinations of his friend’s death, and a desperate urge to communicate something about crime and beauty. His transformation by the war was enormous: he began as a boy who loved Shakespeare and poetry, eager to prove himself a man through combat; he comes out deeply cynical of war and its purposes. He can never go back to the life he had before, or to the faith he had in the empire of England. Yeah, this one's going to be dark.
In the introduction to the 1928 edition of Mrs Dalloway, Woolf explains outright that Septimus and Clarissa are doubles. In fact, she originally planned to have Clarissa kill herself in the end. Both Septimus and Clarissa are disturbed by the social structure and oppressions of British life. They both love Shakespeare (think of the line they both recall from Cymbeline: "fear no more"), are both very attuned to life’s deep meaning, and both have bird-like faces.
The two protagonists also share psychological qualities. Where Clarissa manages to feel nothing after witnessing the death of her sister, Septimus is also initially pleased with his manly, detached attitude toward the loss of Evans. Thoughts of death are central to both of them: Septimus thinks about Evans’ death and Clarissa dwells constantly on her own. Both willingly participate in a lifestyle that validates imperialism, nationalism, and war. And while Clarissa manages far better than Septimus, they both manage to see beauty in the world in spite of the suffering and isolation.
Septimus succeeds in slapping convention in the face, but is only able to do so by killing himself. His death is experienced by Clarissa as an expression of defiance, a real communication of the self, from which she can benefit, too:
A thing there was that mattered; a thing, wreathed about with chatter, defaced, obscured in her own life, let drop every day in corruption, lies, chatter. This he had preserved. Death was defiance. Death was an attempt to communicate; people feeling the impossibility of reaching the centre which, mystically, evaded them; closeness drew apart; rapture faded, one was alone. There was an embrace in death. (6.86)
Neither Woolf nor Clarissa consider Septimus' death a tragedy per se; it’s more like the ultimate acknowledgment of the failures of the world around him – a bold rejection of tyranny and the only way to preserve himself. He therefore "plunges holding his treasure" (6.87), as Clarissa describes it, which is to say that he has held on to part of himself and his dignity.
Dr Holmes has been treating Septimus, although he does not take his patient’s problems seriously; nor does Septimus have any respect for Dr Holmes. Conversely, Sir William Bradshaw immediately sees there’s a problem with Septimus. The only trouble is that his philosophy of wellness – based on Proportion and Conversion, and other things we luckily don’t believe in today – has a creepy scientific and inhuman sound to it, and involves Septimus being placed in one of his mental homes, away from everything he cares about. Septimus is clearly affected by post-traumatic stress disorder, but the only mention Bradshaw makes of damage from the war comes at the party, where he says there should be some governmental provision regarding shell-shock.
Under the care of these doctors, Septimus senses that they’re part of the same authoritarian system that controlled the war. As these doctors see him, Septimus is a danger to society because he serves as a reminder of the damage of war, instead of the heroism. He must be put away so people can still believe in the grandness of English empire. Talk about using someone.
Septimus’ madness derives from many things, namely feeling deeply isolated from everyone, with a big lack of understanding and empathy. It seems like the entire world is against him: "The world has raised its whip; where will it descend?" (1.32). Although his wife, Lucrezia, tries desperately to help him, she, too, longs for everything to be normal. In any case, Septimus' writings are the only way he can express himself:
About war; about Shakespeare; about great discoveries; how there is no death [...]; how the dead sing behind rhododendron bushes odes to Time; conversation with Shakespeare; Evans, Evans, Evans-his message from the dead; do not cut down trees; tell the Prime Minister. Universal love: the meaning of the world. (5.140)
Though Septimus believes he has no feeling, he actually has an excess of it. He is too sensitive for the world in which he lives. Like his wife, he is a foreigner, but in terms of social conformity, rather than national identity. We wonder which of those feels more disconnected.