Just prior to the end of the summer semester, after which Sinclair is scheduled to reluctantly return home, he is in his room, thinking about Frau Eva, willing her to come to him with as much psychic force as he can muster. Responding to the sudden sound of a horse in the street below, Sinclair descends to meet Demian, who announces the beginning of the war and his commission as a lieutenant. Demian also informs Sinclair that it was Frau Eva who sent him and that she sensed his call.
Sinclair has that evening's meal as Frau Eva's only guest. Just as he is about to leave, she informs him that whenever he needs her, all he need to do is appeal to her in the same manner as he had that day.
The following winter finds Sinclair on the front lines. As a participant in the war, he senses that the horrible fighting and death that he observes all around him are merely different types of signs for the same principle represented by his sparrow hawk. The manifested hatred is not in actuality directed toward the enemy but is rather directed violently at the divided individual soul, which must first be destroyed before it can be reborn.
One night while on guard duty in Belgium, Sinclair is gazing at the sky while braced against the trunk of a tree. The tree as a location for the occurrence of an enlightening experience becomes a strong motif in Hesse's writings from Demian on. In the clouds, Sinclair visualizes a city teeming with people. Suddenly there appears a godlike giant figure resembling Frau Eva. She swallows up the people, figuratively taking them back into the womb. In resultant agony, she falls to the ground, the "mark" bright on her forehead. As she utters a terrifying scream, thousands of stars spring from her forehead. One of these stars, actually a piece of shrapnel from an explosion, reaches Sinclair, seriously wounding him. Hesse's source for this scene is obviously the account of the Daughter of Zion in the Book of Revelations.
After a period of vague consciousness, Sinclair finds himself in a field hospital. Turning on his mattress, he notices that the mattress beside his is also occupied. It is Demian. Quietly making brief references to the past, even to the long, unmentioned Kromer episode, Demian calmly tells Sinclair that he will soon depart, but that the next time he is needed, all Emil need do is to listen within and he will find him. As a final gesture, he gives Sinclair a kiss from Frau Eva.
Upon reawakening, Emil finds the neighboring cot occupied by a stranger. The transubstantiation complete, Sinclair has now internalized Demian. The synthesis is finished; Demian and Sinclair are one. The conscious ego (Sinclair) has merged with the self (Demian) and, through Demian, with the anima (Frau Eva). At least to as great a degree as possible for Sinclair, harmony is achieved. In his last comment, he states that dressing the wound hurt as has everything that has happened to him since. Sinclair has not attained the perfect rapture which he has sought, but he has had a taste of it. The answer to the pain of living, he has learned, now lies within him. He has achieved awareness and inner peace and can subsequently draw upon this when life places obstacles in his path.
It should be noted that the only Hesse hero to achieve complete, permanent fulfillment or a state of Nirvana is Siddlhartha. In conclusion, it is important for the reader to remember Hesse's own statement about Demian and Frau Eva. While they certainly are real characters in the story, they also have a profound influence on Sinclair's mind and, at times, necessarily seem like only parts of his mind. Their existence and activities cannot always be rationally explained, but they need not be; they are the products of Hesse's "magical thinking."