Simon the Coldheart by Georgette Heyer

He struck a week before the promised date, and the manner of his striking was typical of his policy throughout his career. His mine ran from the camp beneath the town-walls to a corner of waste ground within the town. He had made his calculations exactly, a rough plan of Belrémy as his guide. Two hours' work would make an outlet from this subterranean passage.

Simon called a council of his captains on the day before his attack, and laid his last commands upon them. Holland was there, a youngster, unskilled in wars, but brave as a lion, and eager; Geoffrey, dark and tall, peerless in attack, and Alan, dreamy and nonchalant, yet ready to obey any order, blessed with the Montlice dash and verve whenever necessity called. They gathered together in Simon's tent, unwontedly grave. Huntingdon was clad in leather, his armour laid by, and sat upon a rude bench, leaning forward the better to keep his eyes on Simon. Geoffrey stood before the table, fully equipped, but Alan had drawn a stool near to the entrance of the tent, and was dressed in soft cloth and silks. He rested his head in his hand, and his eyes were upon Simon, wide-open, and shining with a childlike innocence. Simon himself sat at the table, plans before him, in such a way that he might look easily from one to the other of his captains. His hands were loosely clasped upon the rough wood; he frowned, but his voice was passionless and even.