In addition to establishing the "momentary, illusory, special and separate peace" for the boys with the Winter Carnival, Phineas, for the first time since his accident, becomes active again and generates his influence upon Gene because of

his own inner joy at life for a moment as it should be, as it was meant to be in his nature, Phineas recaptured that magic gift for existing primarily in space, one foot conceding briefly to gravity its rights before spinning him off again into the air.  It was his wildest demonstration of himself, of himself in the kind of world he loved; it was his choreography of peace.

Finny generates his own peace and creates an atmosphere that supports his contention that there is "no dreary weather" even though the winter has, as Gene describes it, 

conquered, overrrun, and destroyed everything...all the juices are dead, every sprig of vitality snapped...

Phineas is able to transcend reality and draw others away from it, too.  Gene narrates,

He drew me increasingly away from the Butt Room crowd...into a world inhabited by just himself and me, where there was no war at all, Just Phineas and me alone among all the people of the world....

In the words of Gene, "Phineas has an exuberance which intoxicates the others."

One of Finny's most creative undertakings is Devon's Winter Carnival. As Gene pointed out, Devon did not have a Winter Carnival, which did not deter Finny at all in putting one together to break the monotony of the gray New Hampshire winter. After smuggling materials out of their dorm (including some jugs of hard cider), the boys established the site of Finny's most recent adventure in the small park beside the Naguamsett River.

Once the Winter Carnival was underway, the boys lost themselves in fun and games, literally, with some help from the cider. All thoughts of war were banished for the afternoon as they simply enjoyed the freedom of being young and alive. Gene remembered what he felt that afternoon, and his feelings were shared by the others:

It wasn't the cider which made me surpass myself, it was this liberation we had torn from the gray encroachments of 1943, the escape we had concocted, this afternoon of momentary, illusory, special and separate peace.

Finny's Winter Carnival creates for himself and the others an illusion of peace; for a little while, it takes them away from the reality of war, death, and ever-present fear. Very symbolically, it is Leper's disturbing telegram that brings the boys' joy to a sudden, sobering, and unexpected conclusion. They cannot escape reality for very long.