Grf. Welsch has writen already on the hasty defense. If time is available every attempt should be made to strengthen your position. The first thing you should do is provide yourself some warning about the enemy by putting an outpost in front of your position. The purpose of this outpost is to warn you of the enemys approach, delay the enemy, fool the enemy about your exacte location but most of all for your own safty. An outpost will allow you to set aside your weapons and start digging in. Just as in the hasty defense several firing positions should be chosen. At this point the reality of war and the practicallity of reenacting depart from from each other. The next thing would be to set up barriers to the enemy's movement, barbed wire, anti-tank obsticles, mines. Then positions should be dug in deeper and overhead cover should be added. For practial purposes you should use any additional time to improve your fighting positons and to check your line of sight and avenues of approch.
If you have the time and equipment, communications should be run between the vorposte and the main line, and between squads and other supporting elements.
With that in mind here is how a typical German Defensive line should look.
5,000 to 7,000 meters from the Hauptkampffeld (Main Line of Resestance) a Vorgeschobene Stellung (Advanced Position) is set up. Since these units are too far from the MLR they must be very moble. They will probably be composed of Divisional Recon detachements and are supported by artillery fire only. They will occupy major terrain features such as river crossings, railways and cross roads. High elevation is also important for them since this allows them observe over a larger area (for artillery) and to deny these points to the enemy.
Next is the Vorposten which is 2,000 to 5,000 meters to the front of the MLR, however it must be covered by the supporting fire of the MLR. Since very few reenactment units have 12 cm morters or 7.5cm infantry guns the vorposten should not be beyond the range of the parent units fire 100-200 meters. The vorpost should have a covered means of retreat, they should engage in combat briefly and then withdraw when pressed by a supirior force. When withdrawing the germans typically will not allow and enemy to close with them to a range less than the distance to the next position they have to their rear. Effective ranges for reenactors of course are much shorter but the outpost should not allow the enemy to come so close that they are trapped in their position.
Both of these forward positions are very far apart and so need to be suplemented by routine partols to insure security.
Next is the Hauptkampffeld Stellung (HKS). For a German Platoon the normal frontage is about 200 meters with squads occuiping 30-40 meters. The squads are not set in a straight line but should be able to cover each others flanks with fire or fire into adjasent positions if the defenders there are driven out. This fire will facilitated the counter attack to retake the position which is a major principle of German defense.
A typical German defense would be to have one platoon forward in outpost positions. The other platoons will be drawn up in line behind it. When the outpost platoon falls back they go through the main line and occupy a position as reserve for the company.
The counter attack must be conducted as quickly as possible to prevent the enemy from consolidating the position or bringing up reinforcements. The flanking squads/platoons should direct fire into the lost position to keep the attackers there pinned down and not allow them to organize their defences. Artillery and mortars are often registered on the positons in advance to facilitate the counter attack.
If time is available the defensive positions will be dug in and built up. The germans stress effect before cover. That means they will dig in first and then work on concealing the position. See the section on field fortificationsfor a general description.