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In the United States the "Takings Clause" of the Fifth Amendment to the Constitution states:
"...nor shall private property be taken for public use, without just compensation."
So, if the government takes land for public use (say for example a factory to be repurposed to produce tanks) they would have to pay just compensation. Just compensation has been deemed to be fair market value at the time of the taking paid in cash. See e.g. Olson v. United States, 292 U.S. 246 (1934) The process is often referred to as Eminent Domain. I should point out that the 14th Amendment to the US Constitution makes the Fifth Amendment applicable to the States.
In the United Kingdom the system is referred to as "Compulsory Purchasing."
The University of Maryland has a nice discussion on takings in general.
So yes, in common law based countries in the west, like the UK, and the US, compensation is likely to be offered, in fact it is required that it is offered.