Upvote:0
The french 75mm field gun (Canon de 75 modèle 1897, which came out in WWI) and was still available in large numbers in 1940 ?
Which was used by France, Poland, Great Britain and the US 1940.
In the case of the US, the carriage was changed into a split trail design.
Upvote:3
Why limit yourself to WW1? The Dutch army went to battle in 1940 with (some) equipment predating the Franco-Prussian war.
added:
I think the question is mood. Why? Because the age of a weapon is not that important. Look at the time period: 1914-1940 = 26 years.
Many advanced weapons systems in common use today are much older:
If we take those examples, and place them against 1914 you'd go back to well before the Crimean War of 1853. That's not possible or even realistic, of course. Sometimes weapons remain in extended use for many reasons.
Upvote:4
More than you can imagine, and not only minor kingdoms.
The main actors of WWII where still using WWI equipment, specially at the beginning.
From the navy standpoint, many main unit where still from WWI (all Queen Elizabeth-class and Revenge-class, for example, for UK) for all the participant. From infantry, lot of equipment was from WWI, here few examples:
Here I've put some examples, the space of the answer is too little to put all the weapons from WWI used in WWII and other wars (for examples, Type 3 machine gun was used still in the Vietnam war).