I wanted to address a point that originally came up in the comments to bgwiehle's answer.
Places are known by different names throughout their history. If a place was called by a particular name during the time the Nazis were in power, it may not be acceptable to use that name in a social setting, for obvious reasons. However, as historians and researchers we need to be aware of the entire historical record, including when the name was used.
If you look up the town in the gazetteer GOV (Das Genealogische Orts-Verzeichnis) at genealogy.net then the results show:
Schmietsch, Lößtal, Śmicz
- Schmietsch (deu)
- Lößtal (1936 - 1945) (deu)
- Śmicz (1945 -) (pol)
However unpleasant it might be to see the name from 1936-1945 listed, to leave it out would be changing the historical record. It is useful for GOV to list all the names so people unfamiliar with the place can see what name is used during each time period.
From a practical standpoint, when a researcher is looking up a town in a gazetteer, one needs to know the publication date of the gazetteer in order to locate the town.
Meyers Orts- und Verkehrs-Lexikon des Deutschen Reichs (Meyers Gazetteer of the German Empire, commonly abbreviated as "Meyers Orts") was compiled in 1912. Ancestry.com's "About Meyers Gazetteer of the German Empire" says:
This gazetteer of the German Empire is the gazetteer to use to locate
place names in German research. It was originally compiled in 1912.
This gazetteer is the gazetteer to use because it includes all areas
that were part of the pre-World War I (WWI) German Empire. Gazetteers
published after WWI may not include parts of the Empire that were lost
to bordering countries. Overall, this gazetteer includes more than
210,000 cities, towns, hamlets, villages, etc.
The FamilySearch Research Wiki article Germany Historical Geography says:
The FamilySearch Catalog is based on German jurisdictions as they
existed from 1871 until World War I, regardless of earlier or later
changes. Places that are now under foreign jurisdiction but were part
of the German Empire in 1871 are listed under both GERMANY, PREUßEN,
[PROVINCE], [TOWN] and also under their present location, such as
POLAND, RUSSIA, LITHUANIA, FRANCE, or DENMARK.
The descriptions for Kevan M. Hansen's German Map Guides series says Hansen uses the place names "around 1870".
This may seem obvious, but my experience is that beginners sometimes get fixated on the contemporary place names, then wonder why it is they can't find the place they are looking for. Even reading the Research Wiki at Family Search doesn't make it clear that the FamilySearch catalog's place name standard for Germany is Meyers Orts -- it's something that experienced genealogists "just know", that doesn't often get made explicit.
Whichever gazetteer or reference work or library / archive catalog you use, it's important to be aware of which time period the work describes or which gazetteer that catalog uses as a place name standard.
The researcher also needs to know ALL the place names because when you see a historical record that came from that place, you want to be able to recognize that the record is from the place you want to look at.
You also need to be aware of the modern-day place names when writing to archives. So in my opinion, you need to have a record of all the names in your research notes, even if some of them are distasteful to you.
When I first wrote this answer, I was unable to locate this town in any of the volumes of Kevan Hansen's Map Guide to Parish Register series. A recent post (11 Jul 2015) on the blog announced the publication of Volume 52. The guides were written
... to help family historians resolve where their family may have
gone to church – and left vital records behind that may be seen today.
The Guides show both Lutheran and Catholic parishes, have information about how far people might have traveled, show population centers, and have information about local archives. The series is still ongoing, so if you are looking for a place and can't find it, it is possible that Hansen hasn't covered that area of Germany yet.
The page at FamilyRoots Publishing which shows the areas covered so far is German Map Guides Subcategories. (For a fuller description of the contents of the map guides, see this answer or look at the detail page for any of the volumes at the publisher's web site.)
Some of the volumes have master indexes for the area covered (for example, Volume 52, the second Posen volume, contains a master index for both Posen volumes). I don't know if anyone has produced an online cross-reference that would allow looking up a town name to get which volume the town might be in -- I tried doing a Google site search of the Family Roots site for Schmietsch and Schmitsch, Schlesien and Silesia, but I did not see results for the Map Guides.
However, on 2 March 2016, Family Roots posted on their blog: Map Guide To German Parish Registers Vol. 55 – Province Of Silesia lII, RB Oppeln – Now Shipping. This post lists the cities included, and Schmietsch is on the list, so we can see that this is the volume you need.
The publisher says:
Each volumes of the series does the following:
- Identifies the parish where an ancestor worshipped based on where they lived.
- Gives the FHL microfilm number for the family’s parish records.
- Identifies nearly every city, town, and place that included residents.
- Visually identifies church parishes for Lutherans & Catholics in each district.
- Identifies adjoining parishes in case an ancestor attended an alternate parish.
- Aids in area searches, particularly across district or regional borders.
- Provides visual identification of search areas in which to look for a family.
- Helps in determining proximity of one area to another.
- Aids in determining reasonable distances of travel from one area to another.
- Identifies population centers in each parish.
- Identifies archives, repositories, and other resources.
- Aids in identification of the location of minority religions.
Volume 55 also holds the master index for all the Silesia volumes.
The map guide could tell you which archives and repositories hold the original materials for this town.
Mark & Becky Rabideau's site Many Roads has a Mega-search Engine which uses Google to look for lesser-known resources. They also have a useful page of links, historical maps, and other resources. The site started out with Mark sharing material from his own research. New resources are being added all the time, so it is worth keeping an eye on.
Update: at the time I wrote my original answer, I was unaware of the project Meyersgaz.org, a website that makes Meyers Orts- und Verkehrs-lexikon des deutschen Reichs easy to use by ordinary users. From @BradC's comment (posted Apr 4 '16 at 18:25):
There is a new website available, meyersgaz.org. This website has indexed the Meyers Gazetteer and linked in historical maps. You can view Schmietsch at meyersgaz.org/place.aspx?id=20732021. If you go to the Ecclesiastical tab you'll see nearby places and whether they had a Catholic or Protestant parish. This may help you in your search.
http://www.meyersgaz.org/ is a beautifully-designed website that is the work of two dedicated individuals. See the Help for more information on how to use the website.
It is also possible to find a place by the brute-force, old-school way, by searching and viewing Meyers Gazetteer of the German Empire which is free on Ancestry in book form, and using Karte des Deutschen Reiches at the David Rumsey Map Collection, but having the two resources linked as they are on meyersgaz.org saves a tremendous amount time and effort.
FamilySearch's Learning Center Lessons has a video here: Meyer's Gazetteer Now Online, Indexed and Fully Searchable!, and live webinars are offered from time to time as Family History Library webinars. For more information, see the FamilySearch Wiki article Family History Library Classes and Webinars and open the section International Research Webinars under Upcoming Webinars.