D.P. Sayler was an active and leading church during the latter half of the 1800s. He was ordained as an elder in 1850 shortly before his 40th birthday and by the time of the Civil War he was one of the outstanding leaders in church. Sayler was an early and active promoter of missionary activity and a prolific contributor to Brethren periodicals.
In 1859 Sayler was the first person to be referred to as moderator of the Annual Meeting. The term was first used in the 1850s and initially those who served as moderator were not named in minutes. Sayler also served served as moderator in 1860 and again in 1877. Sayler also served on a number of Conference committees, including "investigating committees" assigned to visit congregations that were having difficulties. He vigorously defended the policies of Annual Meeting.
Although Sayler was evidently sympathetic with the Old German Baptist Brethren in many ways and some of them assumed he was on their side, he refused to join them when they separated from Annual Meeting. In 1882 he argued vigorously that the report of the Berlin Committee which recommended the disfellowship of H.R. Holsinger must be accepted in order to maintain the integrity of the Annual Meeting.
At the same Annual Meeting, Sayler was responsible for the so-called "Mandatory Resolution" which required all Brethren congregations to follow the decisions of the Annual Meeting. This was an issue the church had been dealing with since at least 1842. There were those who felt that the authority of Annual Meeting should be more binding, while on the other hand, there were others who believed that congregational autonomy must be respected. The old German Baptist Brethren withdrew from the main body of the church in 1881 when their insistence on a rigid enforcement of the decisions of Annual Meeting had failed. In 1882, during the Progressive and Old Order Brethren withdrawal, the mandatory character of Annual Meeting decisions was affirmed. Nine districts came to the 1883 Annual Meeting with requests for modifciation or repeal, but no change was made.
By the time Sayler left the Annual Meeting of 1882, he was exhausted and ill. He never fully recovered and died June 6, 1885.