His was one of the original German founding families of Moncton, New Brunswick landing on June 3, 1766, migrating there from Philadelphia under contract with land agent John Hughes of Benjamin Franklin & Co. He was the first settler to sign the contract of January 27, 1766 in Philadelphia, after John Hughes’ own signature. The family was carried to Monckton Township on the single-masted sloop “Lovey” under Captain Nathaniel Shiverick.
The Sommer surname was later anglicized to Summer, and then Somers in future generations.

From Les Bowser:
“He and his friend Valentin Miller, another signatory to the agreement [who signed right below Sommer], became trustees of St. Peter’s Lutheran Church in Barren Hill [north of Philadelphia, a few miles northwest of Germantown, on the upper border of Roxborough], the congregation having been created out of a schism in the Lutheran Church at Germantown. Valentin and Matthias, along with others of their church brethren at St. Peter’s, met on several occasions with Rev. Mühlenberg to discuss church business. In 1765, seven years after initially forming, the members of St. Peter’s congregation found themselves unable to repay the costs of constructing their church, and they wanted to send members to Europe to solicit donations from friends and relatives there. Mühlenberg described Valentin and Matthias as poor men with no property to their names: “Christopher Raben was the only one who possessed some property..Muller, Kolb and Sommer did not possess anything.””
Matthias Sommer lived right near to St. Peter’s Church according to Mühlenberg, thus locating his Pennsylvania home.
On Sep 24, 1765, he was naturalized along with the heads of two other families who would later co-settle Monckton Township, Heinrich Stieff and Michael Lutz, listing Roxborough as their place of residence, Philadelphia County. Roxborough is adjacent to Germantown and now the 21st Ward within Philadelphia, Pennsylvania. Charles Jones also stated his residence in Roxborough, so it is apparent the future settlers were well acquainted with one another.

“German from Pennsylvania. Naturalized at Penboro, Philadelphia County on Sep 22, 1765 (Naturalizations of Foreign Protestants in American and West Indian Colonies, Publication of the Huguenot Society of London vo. XXIV, Manchester 1921, p. 105)”

Professor Hempel thought Sommer’s wife Christina died and that Matthias re-married Maria Magdalena Aldmann in Philadelphia because there is a record of this marriage in Frankford, Pennsylvania on Aug 15, 1758. However, it seems there were two Matthias Sommers in Philadelphia causing this confusion. There was a “Matthias Sumer” who arrived from Rotterdam on the ship Anderson on Aug 25, 1751 (i.e. two years after the marriage in Philadelphia between our Matthias Sommer and Christina Nullin, 'Nullin' being the feminine form of 'Null' in old German).
The original list of settlers from 1766 ( seen at http://www.ourgenealogy.ca/Canada/NewBrunswick/NewBrunswickMaps.html ) clearly lists Matthias’ wife as “Christiana” with their six children.

The family’s first winters on the lands of Monckton Township were gruelling as documented by several sources. A letter from William Franklin to his father Benjamin Franklin on Oct 23, 1767 reports: "Mr. Jacob [sic - John] Hall (who keeps a Tavern at the Wheat sheaf near Frankford, and has been lately at Nova Scotia with Settlers for your Company of which he is likewise a Member) complains heavily of the narrow spiritedness and Mismanagement of Mr. Hughes and the other Members. They impowered him it seems to conduct there a Body of Settlers, and to furnish them with such Necessaries as they should have Occasion for till they could subsist themselves; but tho’ he gave them Nothing but what was indispensably [necessary] they refus’d on his Return to acc[ept his] account. This put it out of his Power to return again to Nova Scotia, he having bought Provisions, &c. there on his own Credit. By this means Numbers who had engag’d to accompany Mr. Hall, on his Return, were deterr’d from going, which has greatly retarded the Settlement. And the poor People who were left there last Fall, and who, as they were not yet able to raise any Thing for themselves rely’d on a further Support to be brought by Mr. Hall were during the whole Winter in the greatest Distress imaginable, and must infallibly have starv’d had it not been for Lieut. Gov. Franklin and Capt. Houston an old Settler in that Province, taking Compassion on them. These Gentlemen sent them Supplies from Time to Time in Confidence that the Company were Gentlemen of too much Honour not to repay them." A later letter from surveyor Charles Baker to John Hughes on July 24, 1769 reports with the interesting spelling of the time: "They beg you would let them have some Working Cattle and Some Cloaths and Provisions untill they will be able to Raise it to themselves which they think will not be long. I think it is a Very Great Pitty that they should be lett Suffer so much as they have done ever since they went there as they are a Set of the Best Settlers in them Parts it has Surprised every one that knew them to see how they have lived since they went there Mostly on Herbs which they gathered in the Marsh in the Spring etc."

Matthias had died by Mar 3, 1768 at which time his remaining family is mentioned in a letter from land agent Anthony Wayne to supplier Samuel Weathered. His wife and kids then merged families with the family of recent widower Jacob Ricker, Jr.

From the Chignecto Post published in Sackville, Westmorland County, New Brunswick, January 14, 1886:
“The Pioneers of Westmorland (Judge Botsford lecture) .. The next immigrants who settled in Westmorland came to Petitcodiac (West. Co.) They left the Rhine in the year 1749 and proceeded to Pennsylvania then a British Colony. They ascended the Deleware and purchased and improved lands on the Schuylkill about twelve miles above Philadelphia. After remaining about 14 years they removed to this county under the impression that they could easily obtain large tracts of lands. It is said that these immigrants consisted of eleven families, but after much inquiry, I can only identify nine, being - STEEVES, LUTZ, SMITH, RICHIES, SUMMERS, TRITES, JOHNS now JONES, WORTMAN and COPPLE. They left the Deleware in the year 1763 and touched at Digby, N.S. That part of the country at that time to which settlers were first attracted, Port Royal (now Annapolis), was a large garrison town. They remained there but a few days and proceeded up the Bay and finally landed at Hall's Creek (port of Moncton) at that time called Panscada Creek. Hall was master of the ship which brought the immigrants and landing gave his name to the Creek. This I had from one of the oldest inhabitants who is now dead. Old Mr. STEEVES settled in Hillsborough and some of his sons on the Petitcodiac. Old Mr. Steeves family on his arrival consisted of seven sons. ... May 21, 1772, another lot of immigrants came from Yorkshire, England. The late Charles DIXON with a few families, 62 persons in all, arrived at Fort Cumberland and in the following year some forty families joined them. Their names were METCALF, WELDON, DIXON, KEILLER, HUMPHREY, FAIRWATHER, HARPER, BALLOU, WELLS, ROBERTS, WATSON, GRACE, STONE, HARRISON, RICHARDSON, CHAPMAN, COOK, DOBSON, FOSTER, FRASER, OULTON, COLPITTS, FENTON, MITTEN, THOMPSON, BULMER, RIPLEY, BROWN, CARTER, KING, SIDDAL, TRUEMAN, TOWER, ROBINSON, SMITH, LOWERISON, LUSBY, BLACK, Chas. THOMPSON, TURNER, WRY, SNOWDON, FAWCETTS, ATKINSON, TRENHOLM, COATES, BLINKHORN, PIPES. Some settled in Sackville; some in Dorchester; the Colpitts, Fentons and Mittons in Cumberland. In Oct. 1782, the late Amos BOTSFORD arrived at Digby, N.S., moved to Fort Cumberland in 1785 and finally settled in Sackville. The CHANDLERS also arrived at the same time.”