After the separation from the original parish of Attendorn, around 900, St. John's Chapel is not only the center of a flourishing village, but of a parish that extends over the southern half of the current district of Olpe, like, by the way, the deanery of Olpe, which was founded in 1923. The old patrocinium of St. John was replaced only around 1700 by that of St. Martinus, venerated as the local saint. Since then, his "mantle donation" has its place in the church seal as well as in the town coat of arms.
During the town fire in 1795 the then parish church was severely damaged. On July 23, 1907, on the feast of the diocesan patron St. Liborius, the foundation stone of the new church was laid. On June 10, 1909, the Corpus Christi procession enters the new church. The people of Olpe are proud of their new St. Martinus Church, which is one of the largest and most beautiful in the Sauerland. In 1922 the new bronze bells Martinus, Agatha, Rochus are consecrated.
On March 28, 1945, 72 British bombers with over 30 accompanying fighter-bombers destroy railroad lines in Olpe. 43 bombers attack Olpe with five bombing raids, killing more than 200 people. St. Martinus Church is so badly damaged that the southwestern steeple has to be blown up. The tower structure, which is about 35 meters high, was not rebuilt. Today, the ruined tower is seen as a memorial for peace.
In the southwest tower, which was partially blown up in 1945, an adoration chapel was set up in 2013 for Maria Theresia Bonzel, the founder of the Olpe order who was beatified in the same year, and the grave of the blessed is also located there. Her mortal remains were transferred from the previous burial chapel at the motherhouse of the order to the parish church on November 12, 2013. Worth seeing the windows above this chapel: they are the only original windows. They were not yet installed at the time of the bombing of Olpe, so when the church was hit, only the temporary windows were destroyed. Thus, after the reconstruction, the intact original windows could be installed here, while all other church windows are new productions from the post-war period.
Source: http://www.pv-olpe.de/10923-Gemeinden/10689-Pfarrei-St.-Martinus-Olpe/74061,Die-St.-Martinus-Kirche-in-57462-Olpe.html, as of 2/24/2017 and https://de.wikipedia.org/wiki/St.-Martinus-Kirche_(Olpe), as of 11/24/2017.