The Wikipedia entry for the history of Martinez (the city) begins as follows:
In 1824 the Alhambra Valley was included in the Rancho El Pinole Mexican land grant to Ygnacio Martínez.
The reference for this information is given as the webpage of the Martinez Historical Society, whose text reads:
In 1824, the Alhambra Valley was included in a 17,000 acre land grant awarded to Don Ygnacio Martinez by the Mexican government for services rendered to the Royal Spanish and Mexican armies.
Aside from the fact that the source gives the size of the land grant while the Wikipedia entry gives its name, and that the former is more complete, another difference is that the city’s eponym is cited in Wikipedia as Martínez (with an accent in the i) and by the MHS as Martinez (with no accent).
In Spanish, surnames of the -ez type require an acute accent on the penultimate vowel to indicate that this vowel is stressed. (Never mind the peculiar American habit of stressing names like Perez and Chavez on the last syllable.) But this rule was not in effect in 1824, or in 1849 when the city (then only an unincorporated town) was named. In fact, as late as 1913 a Spanish instruction book published in London (The Spanish Language as Now Spoken and Written, by R. D. Monteverde), includes the following:,
I have been unable to find the year in which the Royal Spanish Academy introduced the new rule, but a search using the Google Ngram Viewer for such pairs as Fernandez/Fernández, Martinez/Martínez, Lopez/López and Perez/Pérez shows that the change took place largely between 1870 and 1890. An 1881 book (Memorias de un setentón by Ramón Mesonero Romanos), which I consulted extensively while writing my novel Prince of the Peace, still follows the old rule.
It therefore seems to me that to use, when writing in English, the modernized Spanish spelling of an early-19th-century Californio’s surname is just as much of an anachronism as it would be to respell his first name as Ignacio.
But Wikipedia does more than that. In the introductory paragraph it gives the “Spanish” pronunciation as /mɑrˈtiːnɛθ/ mar-TEE-neth, as though the pronunciation prevalent in northern and central Spain were the one appropriate for a Mexican subject. And it explains the name as “meaning: Martinson”.
Now, there is no element in Martínez that carries the meaning of “son”. It’s true, the names of this type began life as patronymics, and remained so until the 13th century. It’s also true that in many places the meaning of such names is explained as “son of …” This is in part a mistranslation of the corresponding Spanish hijo de… The Spanish language is one in which, at least traditionally, the masculine includes the feminine. Thus padres means ‘fathers’, but it also means ‘parents’; reyes means ‘kings’, but also ‘king and queen’; hijos means ‘sons’ but also ‘children’.
There is some similarity here to Hebrew: the Israelites who are referred to in the Hebrew Bible as B’nei Yisrael (literally ‘sons of Israel’), are called ‘children of Israel’ from the Wycliffe Bible on.
Indeed, the -z ending for patronymics was used for daughters just as for sons: the daughters of Rodrigo Díaz (“El Cid”) are known as Cristina Rodríguez and María Rodríguez, just as his son was Diego Rodríguez. In other words, hijo de should be rendered as ‘child of’.
While there is no single theory of the etymology of the -z patronymics in Spanish (and their -s analogues in Portuguese and Catalan), the most widely accepted one is that the origin is Gothic, that is, Germanic, and corresponds to the common Germanic genitive ending -s. Surnames of this name are common in the Western Germanic languages, and plentiful in English: Jones, Edwards, Richards, Michaels, Peters…
A confirmation of the genitive nature of the ending is given by the fact that in Latin documents, when a patronymic is given, it usually takes the form of the Latin genitive. King Peter I of Aragon and Navarre, the son of Sancho V, appears in one document as Petrus Sancii (the genitive of Sancius, the Latin form of Sancho) and in another as Petrus Sangiz (an approximation to the vernacular form whose modern spelling would be Sánchez).
It follows that, etymologically speaking, such English surnames as Harris, Michaels and Peters are exactly analogous, in substance and form, to the Spanish Enríquez, Miguélez and Pérez, respectively.