Here are the rules taken
from my 1986 Stratego game.

There are two noticeable differences
between the two sets of rules listed above.

1) With the first set of rules, (the set of rules printed on the inside box cover) SOME sets state that:

The Scout may not move and strike in the same turn.

Other sets with rules on the box cover (sets that were printed later) do NOT mention this rule. And NONE of the sets with rules printed in the enclosed booklet mention this.

2) The first set of rules, in the section Rules for "Strike" or Attack, states:

The piece with the lower rank is lost and removed from the board. The winning higher ranking piece is then moved immediately into the empty square formerly occupied by the losing piece.

If the winning piece is the one that is struck (in other words, the losing piece is the one that is "striking" the other) I don't believe Milton Bradley ever intended this winning piece to move into the empty square formerly occupied by the losing piece, as stated above. (That's not even natural.) Remember, the above rule is in the Rules for "Strike" or Attack section; the rule is referring specifically about striking and yes, if the striking piece is the higher ranking piece, then again yes, this piece is then moved immediately into the empty square formerly occupied by the losing piece.

Notice the second set of rules make this very clear.

To clarify, the above rule in red, read on its own, implies the winning piece is moved into the square formerly occupied by the losing piece. But if you take it into context, since this rule is talking about striking, the actual meaning, to me, is clear.

Before playing, it would be wise to confirm which set of rules you and your opponent should use.

Don Woods wrote:

I'm less certain than you about the question of whether the winning piece in an attack always moves into the loser's space.  You said it doesn't make sense and the context around the rule makes you think the winning piece does not move unless it initiated the strike.

I call your attention to Rule 10 in the section on Strikes in the box-lid rules.  The rule explicitly states that "The Bomb does not move into the empty square."  That rule would not be necessary unless the other pieces, when attacked, DO move into the attacker's space if they win.

I'm not really sure which way the rule is intended to be.  I do think it makes some sense that an attack can be used to force an opponent's piece to move.  Not only does it have some value within the game (so the loser still accomplishes something by spending his turn initiating the strike), but it makes some military sense as well: the victor must chase down the loser in order to finish him off!

Don,

Excellent observation on Rule 10 regarding the bomb! However, at this moment I'm still inclined to believe the winning piece was meant to remain where it was, if this piece was the one that was struck... for one other reason I did not mention.

When the rules were reprinted in the later editions, I don't think Milton Bradley CHANGED any of the rules.  I don't believe MB did any testing/experimenting and decided changing the rules made for a better game.  (MB was never keen on that with any other game.)  I'm more inclined to believe they just REPHRASED the rules, believing that they were badly worded.