In a defensive war, you defend your borders. You do not take other people's land.

“Menahem Begin, the Leader of the Irgun, tells how ‘in Jerusalem, as elsewhere, we were the first to pass from the defensive to the offensive...Arabs began to flee in terror...Hagana was carrying out successful attacks on other fronts, while all the Jewish forces proceeded to advance through Haifa like a knife through butter’...The Israelis now allege that the Palestine war began with the entry of the Arab armies into Palestine after 15 May 1948. But that was the second phase of the war; they overlook the massacres, expulsions and dispossessions which took place prior to that date and which necessitated Arab states’ intervention.” Sami Hadawi, “Bitter Harvest.”