He belonged to the school of Benedict Oxenstjerna and was therefore an avowed advocate of a pacific policy. He protested in vain against nearly all the military ventures of Charles XII, e.g. the War of Deposition against Augustus of Saxony and Poland, the invasion of Saxony, the raid into the Ukraine. Again and again he insisted that the pacific overtures of Peter the Great should at least be fairly considered, but his master was always immovable. Piper's career came to an end at the Battle of Poltava (1709), where he was among the prisoners. The last years of his life were spent in exile in Russia. He died at Schlüsselburg in 1716.