I was researching my family tree and came across some very good links that helped me find Polish Military Records and lists of Polish Military and civilians that were victims of Repression by the Soviets and the Germans.
For the Soviets try INDEKS REPRESJONOWANYCH and select "Searching in the database" you can enter all or part of the name,
For the Germans, try straty and select "Search in Database"
Both of these are very useful as often they provide the place name of the arrest (usually where they lived) and often the names of the parents (Imie Ojca - Fathers name, Imie matki, mothers name). Find those with the same surname with the same parents and you're away.
Both databases show what happened to your relatives in terms of where they were interned.
Many ended up in camps in Africa and you can use the passanger manifests on here to find their onward trips (usually about 1948)
Using these methods, not only did I discover many "lost" relatives, but also the names of my great-grandparents which had been forgotten my my own aged parents.
For Polish Military Records:
The British Ministry of Defense is the official custodian of all Polish military records from 1939-1946. They have almost all records of all Polish soldiers who have served under the British Command. Only relatives and the soldiers can obtain a copy of these records in the English language. Replies are usually within 30 days. Be sure to include your relationship with the soldier, or a soldiers document and give as much information as you can to help them search their files.
The MOD still gives free British medals to relatives and soldiers. Poland has stopped doing this in 2000 and as a result they are very rare and hard to find.
Ministry of Defense
APC Disclosures 5 Polish
Building 28 B, RAF Northolt
West End Road
Ruislip, Middlesex, England., HA4 6NG
Pre-WWII rcords. 1918-1939 if not destroyed, can be obtained from the Polish Military Records Center in Rembertow-Warsaw, Poland. AK, Home Army, 1939-1946 records and those of the Polish Peoples Republic 1943-1946 are very difficult to locate and maybe in Rembertow. The address is:
Centralne Archiwum Wojska
Warsaw-Rembertow, Poland 00-910
Data on personnel that served in the Polish Army from 1918-1939 and data of the personnel of the Polish Communist Army can be obtained from :
Aachiwum Instytucji Ministerstwa Obrony Narodowej
Finally, the following address is a collection of vital records from the areas that were previously part of Poland before WWII which became a part of USSR following the Soviet invasion of 17th September 1939 and were formalized as permanent part of the Soviet Union after the was:
Archiwum Akt Zabuzanskich
Urzad Stanu Cywilnego
ul. Jezuicka 1/3
The time frame between the initial enquiry and receupt of info can take up to 4 months.
Costs may vary.
Good luck with searches.
This info might be helpful for tracing relatives, finding out about unknown family members fates, compiling data on rank, decorations, awards, units etc .