1472 : The brethren of Our Lady of the Assumption has an organ installed in the chapel they own in the church.

1477 : The same group contributes to the purchase of an organ for parish use. This instrument, of which the location and specifications are ignored, was restored four times between 1477 and 1577.

1577 : Completion of the west end organ loft sculpted by Jean Grappin. The organ builder Nicolas Barbier of Laon receives the order for a new organ.

1578 : An agreement is signed on the 11th of May between the organ builder and the parish; the price of the instrument is set at 2 000 pounds.

1580 : Inauguration of the organ by Pierre Aubriot.

1582 : Final completion of the work.

1598-1601 : Renovation of the bellows.

1615 : The parish decides to restore the organ.

1618 : On the 24th of October, an agreement is signed between the organ builder Crespin Carlier of Rouen and the parish. The existing stops will be revised, three new stops will be added to the Great Organ and a “Positif de dos” will be added to the existing case.

1620 : Completion of the work.

1631-1632 :: The organist Claude Aubriot undertakes various repairs. Two new stops are added to the Positif, probably by Crespin Carlier.

1654 : The organ builder Claude de Villers of Rouen restores all the pipework (main case and Positif) and repairs the bellows.

1684 : A complete restoration is ordered from Robert Ingout, organ builder from Rouen. The agreement also includes the addition of two tremulants, the rebuilding of the bellows and the replacement of two stops. The price of the work is 900 pounds.

1751 : A contract is signed between the treasurers of the parish and the famous organ builder Jean-Baptiste-Nicolas Lefebvre of Rouen. The Great Organ Tiercelette is replaced by a Flûte allemande 8 and the Voix humaine 8 is suppressed. A Larigot 1 1/3 is added to the Positif and a Clairon 4 to the Pédale. The keyboards are replaced and a fifth bellow is built.

1769 : The parish decides to undertake extensive work on the organ. This revision and enlargement program is the most ambitious since the building of the original organ. The work is entrusted to Jean-Baptiste Nicolas Lefebvre. The new cases (main case and positif), financed by the duke of Penthièvre, last lord of Gisors, are built by the woodworkers Carbonnier and Greslez and decorated by the sculptor Louis. The installation of the new positif case requires the demolition of the old stone parapet which is replaced by a wrought-iron railing made from two old gates from the cemetery.

1774 : End of the work by Jean-Baptiste-Nicolas Lefebvre.

1801 : Concordat between Bonaparte and Pius VII: the use of the church is officially restored to the Catholic religion. The organ, which did not suffer from revolutionary vandalism, is maintained by its titular organist Girod, who repairs a few pipes of some stops.

1840 : Unplayable because of lack of maintenance, the organ is not used for over a year.

1844 : The work is finished on the 25th of June.

1870 : Rebuilding of the windchests by Merklin et Schütze.

1894 : The Anneessens company is granted the restoration of the instrument. All the stops are revoiced, new pumps and a Cummins reservoir are installed. A new tubular pneumatic windchest and a new swell box are built for the Récit. Four new stops are added.
The new tubular pneumatic swell proved unreliable and soon became out of use.

1927 : Complete restoration by Joseph Gutschenritter. Among the modifications and additions can be mentioned the adjunction of Barker levers, the extension of the pedal to 30 notes, the extension of the manuals to 56 notes, the installation of the first electric blower, the replacement of the Great Organ reeds and the addition of a Flute 32 to the Pedal.

1928 : On the 3rd of June, official inauguration by André Marchal.

1940 : On the 6th, 7th and 8th of June, under heavy bombing, the entire roof of the church and the organ are destroyed by fire.

1946 : In October, the great gable of the west end which was not properly shored up collapses during a storm and destroys what remained of the organ loft.

1957 : Restoration of the nave.

1964 : On the 8th of October, the city council decides the rebuilding of an organ “suited to the importance of the church”. The budget does not permit the rebuilding of an identical instrument.
The specifications are established on the 16th of November. Two projects are submitted to 5 organ builders : Boisseau, Haerpfer-Erman, Gutschenritter, Kern, Schwenkedel.

1965 : A committee is created on the 1st of March, with Francis Chapelet as private advisor. The proposal of Haerpfer-Erman for the second project (a 3-manual and pedal, 35-stop organ) is unanimously approved. Action will be mechanical for the notes and electro-pneumatic for the stops; the instrument will have "en chamade" stops and a tremulant. Francis Chapelet succeeded however to impose the following modifications: the stop action will be mechanical, the principals and mixtures will be 75% pewter alloy (instead of 52% initially planned), the console will be of the classical type with a sliding keyboard coupler.

1965-1967 : Quarrels about the case's aesthetics, multiplication of projects, hesitations and administrative tardiness.

1967 : The chief architect for the "Monuments historiques" allows the rebuilding of a case identical to the former one. The organ builder is invited to manufacture the lower part of the case and is told that the superior section will be made with the sculptures when the instrument will be installed on the loft. French Ministry of Culture will help financing that step.
Approved by the chief architect of the "Monuments historiques", the organ builder suppresses the "en chamade" stops that were initially planned on the account that they don't comply with a French classical organ and that they did not exist on the former destroyed organ.

1968 : The organ is ready for installation. Set against the temporary plaster wall that isolates the work in progress on the loft , the instrument is installed on the floor waiting for completion of the work.

1982 : The loft is ready to receive the instrument. Haerpfer's team takes the organ apart for rebuilding on the renovated loft. Certain ornamental parts that were still missing on the case are added. A V-rank Cornet is added. The organ is inaugurated on the 16th of October by its soon-to-become titular organist, Sarah Soularue.

2006 : Denis Lacorre is chosen to undertake general tuning. On this occasion, the Pedal Mixture is transformed into a IV-rank Théorbe.