Shmuel Bais 11:1

And it came to pass, at the teshuvah (turning) of the shanah (year), at the time when melachim go forth [to war], that Dovid sent Yoav, and his avadim with him, and kol Yisroel; and they destroyed the Bnei Ammon, and besieged Rabbah. But Dovid tarried still at Yerushalayim.