In order to situate properly in time and place the origin of Assumption Church it is necessary to go back to the foundation of Detroit. When Cadillac founded Detroit in 1701, for purposes of fur trade, he invited several Indian tribes to come and make their abodes near the French fort which was named Fort Ponchartrain du Détroit. Among the Indian tribes which came to Detroit was a remnant of the Hurons and the Ouendots (Wyandottes) from Michilimackinac whose ancestors had been Christianised by the Jesuits in Huronia in the second quarter of the 17th century. For more than a quarter of a century after the Hurons' arrival at Detroit the only spiritual ministrations accorded them were supplied by the Recollect (Franciscan) chaplain of the fort at the Church of Ste. Anne. In time these children of the forests asked for a black robe, i.e. a Jesuit, to be their spiritual chief as had been their wont in Huronia and at Michilimackinac. As a result of this plea in the summer of 1728, Fr. Armand De La Richardie, S.J came from Quebec to establish a mission among them. It was given the imposing title of "The Mission of Our Lady of the Assumption among the Hurons of Detroit."
Fr. de La Richardie decided to change the location of the Huron village and mission. The site chosen was on the south shore at the bend of the river on the fields of the Hurons. There they would enjoy the protection of a fort at a place known as "La Pointe de Montréal", where the Ambassador Bridge now crosses the river.
In 1765 the sixty some (French) families living on the south shore petitioned for a parish of their own. Instead of erecting a second religious centre in the same locality, it was decided that the Mission of the Assumption among the Hurons should become the Parish of Our Lady of the Assumption with the care of the souls of both the Hurons and the French settlers. A new church 60 x 30 ft. was built by the settlers to replace the 1749 chapel which was falling into ruins. This integrating development was canonically effected in 1767 when Fr. Potier, the Jesuit missionary of the Hurons, became the first pastor. Beginning October 3, 1767 he opened a new Register of Baptisms and Marriages in which he signed himself as "Jesuit missionary performing the pastoral duties in the Church of the Assumption at La Pointe de Montréal du Détroit." That makes Assumption the oldest continuous parish in the present province of Ontario.
The 1767 parish church was erected on the river front at or near the site of the Indian chapel. This building was of frame construction and served only twenty years. Despite the Suppression of the Jesuits in 1773 Fr. Potier, the last Jesuit missionary in the West, was allowed to remain at his post until his death in 1781.
In response to the urgent plea of the Indians and the parishioners for a successor to Fr. Potier, the Bishop of Quebec sent his Vicar-General to be pastor of Assumption parish. Fr. Hubert was an enterprising man. Immediately he planned to build a new rectory and a church and also to open two schools - one for boys and one for girls. Because nearly all the church lands had been sold by his predecessor, it was necessary to acquire new property. Again the Hurons came to the assistance of their missionary. On March 6, 1782 they made a donation of a tract of land six arpents wide by forty deep, immediately west of the original grant. The present Assumption Church is situated on the eastern half of that property.
Fr. Hubert did not stay long enough to see his projects completed. Only the rectory was built in 1785 when he was chosen Auxiliary to the Bishop of Quebec, whom he succeeded three years later. What he had been unable to accomplish as pastor of Assumption he helped to realize by making a generous contribution towards the construction of a new church, and by sending in 1786 two women from Quebec as teachers to start a school for girls in the parish. Those two objectives were achieved during the pastorate of Fr. F.A. Dufaux, a Sulpician priest from Montreal who was in charge of the parish from 1786 to 1796.
The new church, opened in 1787, was built of timbers (squared logs) and was situated on the eastern edge of the park in front of the present church between University Avenue and Riverside Drive. To pay for its construction the western half of the church lands (Huron Church Road to Rosedale Blvd.) was sold to Thomas Pajot. A painting of that church done in 1804 exists and is entitled "A view of the Straits of Detroit from the Huron Church."
In 1796 when Fr. J.B. Marchand took charge of the parish he reported to Bishop Hubert of Quebec that the parish consisted of 150 families. In June of 1801 Bishop Denaut confirmed nearly 500 members of the parish. The size of this confirmation class is not surprising when we consider that this was the first episcopal visitation in the century-long history of the settlement along the shores of the Detroit River. Fr. Marchand remained as pastor until his death in 1825. His ten-year assistant Fr. Joseph Crevier succeeded him.
In 1826 the diocese of Kingston was erected to direct the activities in Upper Canada. In 1831 Fr. Crevier returned to the diocese of Quebec and Bishop Alexander Macdonell, the first Bishop of Kingston, not having any French speaking priest at his disposal for this predominantly French speaking parish, sent his nephew Fr. Angus Macdonell to be pastor of Assumption. During his tenure plans were developed to build a new church. The cornerstone (of the present church) was laid on July 7,1842 when Assumption was part of the newly-erected diocese of Toronto.
The rectangular church opened in 1845 was deemed good enough for the first Bishop of the London Diocese (which was erected in 1856) to transfer his See to Sandwich and make it his Cathedral in 1859. This entailed the departure of the Jesuits who by their many apostolic labours had written the brightest chapter in the Annals of Assumption parish.
The cemetery which was south of the church in 1848 was too close to the projected residence the bishop wished to build, and so in 1860 Bishop Pinsonneault had the cemetery removed to the present site at the corner of Huron Church Road and Wyandotte Street. The bishop erected a large frame and stucco building of elaborate design, which was called the Bishop's Palace. This so-called palace was not well designed…and only thirty-five years after its erection, the leaky mass of building had to be demolished because it was already considered beyond repair. The next bishop returned the See to London in 1869. Only the chestnut trees remain as a last vestige of Assumption's decade of episcopal splendor. In 1870 the Basilian Fathers of Toronto were invited to take charge of the parish and also of Assumption College which had been opened in 1857 by the Jesuit Fathers.
Fr. Dennis O'Connor was the first superior and under his wise direction in 1874 the graceful tower and sanctuary were added to the church. At the same time a touch of colour was introduced by the installation of the stained glass windows in the sanctuary and apse. The brilliant windows in the main part of the church were erected in 1882 when the whole church interior was painted.
Fr. Jean Joseph Marie Aboulin, a native of France, succeeded Fr. O'Connor as pastor. Through Fr. Aboulin's untiring efforts many church furnishings were obtained that are still with us. In 1883 the Stations of the Cross in oil paintings were acquired. The elaborate stone alter was imported from Caen, France, in 1887. The statue of St. Joseph was donated in 1889, and The Pieta and the statue of Ste. Anne were blessed in 1890. Throughout the following years a number of changes were made to the church culminating in 1925 when The floor in the sanctuary was covered with tile of a strikingly beautiful pattern, and the addition of the communion rail of exquisitely carved Italian marble.
The old sacristy and the retreat chapel needed to be demolished in 1907 due to their poor state of repair. It was decided to build a new chapel to the west of the church, and the construction of Rosary Chapel began. The stained glass windows in the chapel bear the names of the donors, and represent the fifteen mysteries of the Rosary.
Through all these years the pastoral life of the parish thrived. In 1937 at the west end of the parish there were some two hundred families who had been impoverished by the depression, so Fr. Allor decided to bring the church to them, and he erected the mission chapel of The Blessed Sacrament.
New families moved to the area, and the descendants of the original French settlers were joined by peoples from many lands. Today Assumption Parish is indeed a Catholic community, with parishioners from around the world. Many Basilian priests have come and gone, and have left their legacy at this parish. The Basilian Fathers continue to serve at Assumption Church. (Excerpts from "Assumption Parish History" by Fr. E.J. LaJeunesse, C.S.B.)
Quoted from the Assumption Parish Website