Withdrawal scenarios don't tend to work very well in Crossfire because of the nature of the rules. Units deployed in sight-blocking terrain such as woods can use retreat moves to slip out of sight of the enemy, and then can in one initiative withdraw as far as they want, so long as enemy fire doesn't stop them. Chases are similarly tricky to design scenarios for, for the same reasons. This scenario requires one side to withdraw, but there is a twist that makes the game a tough fight for both sides. It should also give you a decisive result without too long a game.
The table has a river about 1/4 of the way in from one end,
crossing the table, with a bridge in the middle. Near the river, a
couple of hills offer good hull-down positions to tanks. There might also be another hill somewhere around the one shown (A). The rest of the table should have a fairly dense scattering of the usual mix of woods, patches of rough ground, hedges, fields, depressions, walls, etc. There should not be clear lines of sight down any of the edges of the table, and there should be sufficient cover for the attacking forces to enter from the yellow table edge without being shot to pieces (ideally perhaps about three terrain features on the table edge itself, which are out of line of sight from the defenders), and the attackers coming on should be required to move a fair way across the table before establishing a line of sight to the bridge. Before the game starts, both players agree on what exactly can be seen from the tops of the hills, which might overlook certain pieces of terrain.
The situation: one army ("attackers") has rushed forwards, throwing its opposition ("defenders") into chaos. The broad strategic situation in the campaign is that the defenders are withdrawing, and the defending troops on the table have been given orders to
withdraw. The attackers are intent on destroying as much of the defending army as possible before it escapes.
Forces: both sides have two companies of troops, one FOO for medium mortars, and a couple of MMGs. The attackers have three or possibly four light tanks/armoured cars, which represent the first AFVs on the scene, being the lighter, faster armoured parts of their army's spearhead. The attackers may also be given a light anti-tank gun, and a soft-skin vehicle to tow it. The defending army gets two heavy tanks, with armour almost impervious to the attackers' guns.
This scenario could be set in many times and places. In France 1940, the attackers would be Germans, with perhaps Panzer IIs and 38ts, and a 37mm ATG, while the French would have Char B's, or perhaps the defenders would be British with Matilda IIs. In 1944, the British might be defending with Churchill VIIs against German Panzer IIIs or the like. The Germans might defend with Tigers, while the allies attack with Stuarts. Ideally, only one of the attacking tanks should be able to pierce the defending tanks' front armour, and even then need a 6 on the PEN die, while the other attacking tanks should need to get flank/rear shots to stand a decent chance of a kill. An early war setting is good, because the heavy tanks of that period often had light guns, so that they are capable of dealing with light tanks, but a hit on one does not mean an automatic kill.
Deployment: The defender deploys first. The defending tanks deploy from the hills to the river (red area); the defending infantry from the river to about 3/4 across the table (blue area). Hidden deployment is not used. The attacking player may deploy up to half his infantry in the features that touch his entry edge. The rest of his forces enter during the game from the end of the table furthest from river (yellow edge). The attacker takes the first initiative.
Victory conditions: the defender gets 1 point per infantry base that withdraws off the bright green edge of the table or moves off the table at the yellow edge, plus 10 points for each tank that exits along the yellow edge. To win, the defender needs to score 75% of his starting points, so for example, if the defender has 30 infantry bases (rifle stands, FOOs, officers etc.) and two tanks, that would be 50 points-worth at the start of the game, so to win he would need to withdraw 38 points-worth of forces. This means that if one tank is lost, it is still possible for the defender to win, but only if he suffers very low losses amongst his infantry. Losing both tanks will lose the defender the game.
The big catch: the bridge isn't strong enough for the defender's heavy tanks,
and the river cannot be forded! To make this extra clear, you could use a model of a wooden footbridge, clearly useless for a heavy tank. So, the defending player has a tough decision.
He could withdraw all his troops across the river and off the table
fairly easily, but this would leave his two tanks unescorted, to make
it across the table against everything the attackers have. Since the
bridge is a bottle-neck for the retreating infantry, he has to decide
how few troops he can get away with defending this bottleneck. He
could leave the heavy tanks back on the hills, where they could slug it
out with the enemy at range, but this would stop him from getting them off
the table, which is his objective.
One must assume
that elsewhere, off-table, is a place where heavy tanks can cross the
river. The retreating tanks, once through the advance force of the enemy's light
scouts, can then make for that on their own. Getting the tanks off
the table, and giving them their chance to make for safety, is the
responsibility of the local infantry commander, played by the defending/retreating player. Once he has seen the heavy tanks
off the table, his job has been done, and the retreating player gets
his victory points.
Meanwhile, the attacking player has a strong motive for not hanging
about. He must get forward, and try to pin down as many enemy troops as
possible, and stop the heavy tanks.
Withdrawing infantry rules: the defending player is allowed to move one stand of
soldiers off-table every initiative for free, or a full platoon with
its officer at the cost of the initiative. This turns the retreating
defenders into an effective counter of initiatives for the attacking player,
telling him how long he has to get forward and get stuck in. Once off table, no forces may return.
Rules considerations: the attacking infantry should be fairly useful in a close-range scrap against the tanks, but not so deadly at range. Anti-tank rifles will generally ping harmlessly off a heavy tank, but late-war Panzerfausts are a different matter. If you have late-war troops with good anti-tank weapons, these should be of limited use. Limiting their range to something very short is a good idea. The defender's troops needn't be good against tanks, and might even be ruled to be especially poor against them. For instance, a maximum of a single section/stand of rifles plus officer might be the maximum allowed against a tank in close combat, and the defender's troops might be -1 in close combat versus tanks, to represent a degree of tank-terror experienced by a losing army.
If players usually use rules that require rolls to be made to see if an AFV bogs down when it moves, these should either not be used, or should be very forgiving. It could spoil the scenario if the defender played very well, but ended up losing just because of an unlucky die roll for bogging.
Many players allow more than one move action per initiative for tanks, and some even allow them unlimited movement, much like infantry. For this scenario, tanks should not have unlimited movement, but rules allowing a small (perhaps one or two pivots maximum) number of move actions per initiative shouldn't spoil things. You don't want the defender to be able to rush both his tanks off in one initiative. In one initiative, the attacker would probably be able to get only one or two armour-piercing rounds off in reaction, and these would have a low chance of knocking anything out.