Armies never tell you what their strategy is, but if you look at the problems they are faced with, you can usually figure it out.
No solution they come up with can be perfect -- wars do not allow for perfect solutions -- but their options are always limited, and they will generally go with the least bad one.
So why has Israel ordered all Palestinian civilians to evacuate the northern part of the Gaza Strip within 24 hours?
Never mind the 24 hours. The Israeli military themselves concede that it will take longer than that for the 1.1 million people who live north of Wadi Gaza, the dividing line they have chosen, to move south of there along the single north-south main road.
The civilians probably have several days before the Israeli ground invasion really gets underway.
What the Israel Defence Force (IDF) intends is to create a "free-fire zone" in the northern third of the strip, where its soldiers can use maximum firepower without killing large numbers of civilians.
That's also why Hamas, which rules the Gaza Strip and planned the recent mass slaughter of Israel civilians in the area around the strip, is urging Palestinian civilians in northern Gaza to stay put.
They need the civilians there to deter the Israelis from blowing up everything that moves, or alternatively to provide mountains of dead "martyrs" for the cause.
But what's the Israeli strategy? Consider the nature of the task the IDF's commanders were given. Priority One: "Root out" Hamas's infrastructure in the strip, killing all the senior commanders but also most of the activists.
Priority Two: Accomplish this job incurring the minimum possible number of Israeli military casualties. Nobody will have given the IDF a maximum acceptable number, but more than a thousand military dead would certainly be regarded as a failure.
Priority Three: Minimise Palestinian civilian casualties as much as fulfilling the two higher priorities permits.
Over ten thousand Palestinian civilian deaths would be a failure, because more than that would cause such outrage globally that the operation would have to be stopped.
The free-fire zone is essential to this concept, because otherwise both Palestinian civilian deaths and Israeli military deaths will be too high.
Whereas if there are no civilians around, you just call in the artillery or the bombers every time you encounter resistance.
That spares the lives of the PBI (poor bloody infantry).
You also need somewhere else to put the civilians while you wipe out the Hamas fighters, so you will have to do it piecemeal: divide the strip up into three zones and move the civilians around so there are none (or as few as possible) in the zone that you are currently cleansing -- beginning with the northern one.
Two further implications of this strategy: you will have to filter the entire population of Gaza (2.3 million people) to weed out Hamas members as you move it between the three zones.
And the Israeli hostages might have to be written off: there's difficulty in extracting them safely from the hundreds of kilometres of tunnels they are being held in.
Bezalel Smotrich, the far-right finance minister in Prime Minister Benjamin Netanyahu's government, has called on the Israeli army to "hit Hamas brutally and not take the matter of the captives into significant consideration".
If Israel is to visit "mighty vengeance" on Hamas, as Mr Netanyahu promises, this is a necessary part of the policy.
And one other thing. Who is going to give these two-million-plus residents of Gaza access to food, water and medical care while they are shuffled from one overcrowded zone to the next over a period that cannot be less than a month?
Either Israel, or nobody at all -- and it's not clear if Israel even has the capacity to do that.
Now comes the big question. If I am right about the Israeli strategy, then can it possibly work?
I very much doubt it, because it is too complicated and it would take far too long. Israel has enough international support after the massacres that it can do pretty much anything it wants to the Palestinians in Gaza for the next week or so, but then the sympathy and the patience start running out.
It's still the least bad option available to the Israeli high command, given what the current government is asking the IDF to do.
And while the strategy is almost bound to fail, it will probably kill fewer people than any other that the Israeli population would accept in its current state of mind.
You are offended by the cold calculations I am making in this article? Then you probably shouldn't support war at all.
Gwynne Dyer is an independent journalist whose articles are published in 45 countries. His new book is 'The Shortest History of War'.
