No, political strength, I think, which (as regards internal affairs in the US) is much more closely tied to economic clout than to military clout.
Suppose Congress did meet on land which was situated in Virginia or Maryland. How, exactly, would that give either Virginia or Maryland any particular influence over Congress than other states have? Even if we could think of a way in which Virginia or Maryland would attempt this, Congress could simply relocate itself to, say, Pennsylvania or New York.
I suspect back in the day a part of the rational for having a federal district was simply so that no one state could claim the status of playing host to the federal government.
A secondary consideration was that - especially with the state of communications at the time - physical proximity to the federal institutions would certainly have facilitated networking, access to information, opportunity to influence, etc. But the fact is that the establishment of a federal district does little to counteract this; the establishment of the District of Columbia doesn’t increase the geographic distance between Washington and, e.g., Baltimore, or erect social barriers that would impeded the development of political networks embracing both places.
A third (and related) consideration was, perhaps, that if states had to concede territory for the federal capital, there would automatically be no pressure to establish the capital permanently in any of the existing major cities - the respective states would not wish to cede Boston, or New York, or Philadelphia, or wherever. So this would do something to ensure that the federal capital would at least start its life somewhat disconnected from any of the existing networks of power.
So I think it really comes down to this; the founders didn’t want the federal government to have a special or privileged relationship with any state, beyond what the bare facts of physical and social geography would dictate. And the establishment of a federal district symbolised and underlined this view of the proper state-federal relationship even if, in itself, it did only a limited amount to give effect to it.