Matt grants Jenny permission to do what in Across Five Aprils?
Matt Creighton first grants his daughter Jenny permission to travel to Washington to be by the side of her beau, Shadrach Yale, who has been critically wounded in the Battle of Gettysburg. He later gives her permission to be married to Shadrach.
Jenny and Shadrach are separated when Shadrach goes to fight for the North during the Civil War. Shadrach had asked Matt Creighton if he and Jenny could be married before he left, but Matt had withheld his permission, because he thought Jenny was too young. When Shadrach is wounded at Gettysburg and is sent to a hospital in Washington, he is found by a spinster aunt of his, who is working as a volunteer nurse there. Shadrach's condition is grave, and during his moments of lucidity, he asks his aunt to write to Jenny, and he calls for her in his delirium. The aunt writes to Matt Creighton, begging him to allow Jenny to come to Washington. She offers to pay Jenny's expenses, and to give her shelter in her own home.
Matthew, who cannot stand to see his daughter suffer "if there be one chance fer her to see (Shadrach) alive", agrees to let Jenny go to Washington. Reunited with the girl that he loves, Shadrach rallies, and although he is "still desperately ill", it appears that he will survive. The young couple soon write to Matt, asking permission to be married, which permission the loving father this time grants.
Jenny stays on in Washington as Shadrach's wife, working in the hospital where he is a patient until he is well enough to be discharged. Eventually, they return home to the Creighton farm together (Chapter 10).