Quite often, the "threat" of doing something, will result in a reaction that you want your enemy to do.
Using the "Flagship rejection rule", allows you to present a strong threat, and yet risk very little in exchange for it.
    By guarding a key BATS, deployed MB, or Sector Base (or SB, but you would want to fully defend a SB, the tactic could still be used there, or indeed any other base introduced, which has a Command Rating of three or higher) with four ships, you are able to force your enemy to commit far more force to kill the base than would otherwise be required. The tactic can be used on any base - although, usually you will not have too many spare ships available for this duty.
    For the example, we will assume the base is a BATS, but if any other base is used, it is important to ensure that no more than two ships have a Command Rating higher than the base (as the Flagship must be one of the three units with the highest Command Rating).
    Our "key location" is a Kzinti BATS (Command Rating 9), which is guarded by a BC (Command Rating 8), FF (Command Rating 3) and a CVE+EFF group (Command Rating 6).
    As it is a key location - and Kzinti reserves could reinforce the BATS, a large portion of the Lyran Navy decides they want the area - and with or without the reserves, the Lyrans WILL own that bit of space "real estate".
    Looking at the odds (which are not good) - the Lyrans will be able to use directed damage to kill any ship, or the whole CVE Group, that you put on the line - and then let you run, while they destroy the BATS - not a good return for potentially causing a cripple.
So what to do?
    First we will withdrawal 50% of the allowed ship equivalents - which is four, so two can leave - and we will need to withdraw the CVE group (as it is a group, it cannot be ignored for minimum force sizes with regard to the Flagship rejection inclusion option).
    Second decline the approach battle.
    We are now left with the BATS, BC, and FF, and we must pick one of the units with the third, or higher, highest Command Rating, so all 3 are valid.
    Let's pick the BATS.
    We now need to create our legal minimum force, which can include or exclude rejected Flagships (player's choice), so that is originally two ships, which reduces it to Zero Ships if we exclude them.
    So our legal minimum force size is the BATS and no ships.
    While the BC and FF safely look the other way, the BATS is killed under a withering fire.
    The BC and FF can then retreat, and join up with the CVE group.
The risk?
    The retreating force can be 'retreated onto' (and more easily now, via the Fighting Retreat rule) - but as it is four ships strong, it might be able to handle the damage better (and do real damage in return) than a smaller force could. Plus you can always retreat the CVE group again and let the FF die on its own.
    It uses up some of your forces, which could have been better used elsewhere.
    The advantages?
Just adding those four ships will significantly increase the required force needed to destroy the BATS.
If reserves also can reach the battle they further increase the attacker's required forces, should they be here to kill the base.
    It will more safely hinder your enemy's supplies and retrograde route (as individual ships get generally overrun by Fighting Retreats).
The ships in question - are not specialist and generally will not see the light of day in other combats, as better hulls would be used there.
    If the attacker does not overwhelm your defending force, the four ships in question could be used relatively safely (BC, 2CVE and the FF in the Formation position). The enemy would need to get nine points of damage to cripple the weakest hull, and you would be doing most likely five-to-ten points of damage back from the four ships, thereby making the exchange fairly balanced - and can then retreat behind the ideally crippled BATs to safely escape.

    The tactic will work with less than four ships - but the effects are diminished (Romulans might be able to use more, but they risk Cloak rolls failing and being left with a ship force of one or more at the minimum force stage!) - so four is the magic number.
    So, picket your BATS in fours, as five is a crowd and three is just not enough for a party!