A tactical error that almost all gaming clans make, including some of the best regular clans, is not maintaining an adequate reserve uncommitted to the perimeter defense directly under the control of the force commander/clan captain.
Clans typically work out a plan of defense usually including a perimeter and maybe a long-range patrol element but once the mission commences have no effective way of adjusting their plans to counter enemy movements or even to cover breaches in the perimeter caused by friendly casualties.
Most military books on tactics discuss the need to maintain reserves. This is because battles are not predictable. Adjustments such as taking action against a weakened section of your frontline, patching up a broken frontline or even to respond to an enemy advance from an unexpected direction all require a reserve element.
Because reserves are not committed to the front, they are not likely to be pinned down under enemy fire. So they are free to move where they are needed most.
Also by being adjacent to the force commander/clan captain, orders can be quickly issued to these gamers by the commander and he or she can see that their orders are carried out.
A simple example of using a reserve element for a base defense is the following scenario of saying one section of defenders (10 gamers) versus two sections of attackers (20 gamers).
The defenders have a position where the enemy has two main avenues of approach. If, as is usual, the gamers are committed immediately to the perimeter defense and they are evenly divided between the two avenues, leaving five gamers at each approach.
In this scenario the op-for attacks from the north, initially with a feigned attack of 5 gamers. Then once the defenders are committed, the enemy hits the other avenue, from the north-west, with 15 players. In this case, the attackers gain a local numerical superiority of three to one. This is enough to overrun most positions even given the inherent advantages such as improved cover, or defending.
If, on the other hand, the defenders maintained a reserve element of say four gamers, once the force commander has identified where the main attack is coming from, can quickly move the reserves to support the defenders positioned against the main attack.
The ratios then become 5:3 against the feigned attack and 15:7 (closer to two to one) against the main attack.
Of course, correctly adjusting the reserve effectively requires the force commander to be fed accurate information about the enemy movements.
Typically, this is done most often by the force commander/clan captain positioning him or herself in a good observation point. If your clan has 2-way radios (which are often used by the clans in woodland Veterans' battles), then the radio-equipped forward observers can accurately report enemy movement and strength information to the force commander/clan captain.
The use of reserves and effective battlefield communications are vital elements to victory and are all components of the necessity to have strong and effective leadership.