Diesel engines in military aircraft

[Volker_Nemsch]

I recently saw a report on television about a new German factory that just has started producing Diesel engines (direct injection type) for small aircraft (Cessna, Piper, etc.). The manufacturer stated that the new engines will have about the same power but only half the consumption of normal aircraft engines. The good effect is that the reequipped aircraft will have nearly a doubled range or a higher payload.

After this report I looked through my records. The earliest use of Diesel engines I found was in aircraft produced by Blohm & Voss and Junkers during the mid-thirties of the twentieth century. Both manufacturers used JUMO Diesel engines (Junkers Motorenwerke).

Was this the earliest use of Diesel engines in aircraft? When did other countries start with such experiments?
Were Diesel engines used in planes during or before WW1 (prototypes and other tests)?

Thanks in advance!
Volker Nemsch