[uberman]

The simple answer is dont lie. Tell the truth if asked but dont offer more information than what they request. Now you dont need to maintain the false context of the lie and it will be much easier to be natural in the interview.

[shivajikobardan]

what is the truth?

[uberman]

You know and stated the truth already.

You left due to a personal conflict. The more you want to twist this into something it is not like a growth opportunity the more of the context of the lie you must maintain. Eventually the maintenance of the lie will catch up to you and will affect they way you interview,

You left because of a personnel matter and if you used the time following your leaving to actually do something else then say so. If you did not then say you have taken the time for your self. If you actually saw the opportunity to prepare for government IT job and leveraged it say so. If you try to say "hey I had a great job but quit to prepare for a job in government" then as a recruiting manager of course I would call bullshit and start to probe.