Invasion of Poland
80 Ausf As were with the 2nd and 3rd Light Divisions. 228 total were used.
Invasion of Normandy
Invasion of France
1/10 of the available tank strength was the PzKpfw 38(t). 228 in the 7th Panzer (132) and 8th Panzer (85) Divisions.
Invasion of Russia
There were 754 available at the start of Operation Barbarossa, which was about 1/4 of the total available tank strength. They were primarily deployed in the 7th, 8th, 12th, 19th, and 20th Panzer Divisions.
By July 1941 there were 763.
By April 1942, loses (even with increased production) had reduced this number down to 522.
After most were withdrawn from frontline combat formations, 229 served throughout occupied Europe up until mid-1944.
Some of the remaining PzKpfw 38(t)s were being used for artillery observation.
After World War II
After the war ended the Swiss Army took some of the vehicles and used them.