Ground units in A&A are very important. Without them it is impossible to win the game. Infantry has the best cost-value ratio in the entire game and should be therefore the backbone of every army. The production of armors makes only sense up to a maximum number of armors and a specific arm/inf ratio. It is needless to say that the maximum number can vary from match to match, which makes it difficult to nominate one. However the ratio should be less than 1 armor per 3 infantry units.
Although an ?Infantry only? strategy can be played consequently and successfully, a game without infantry would not lead to success. (An exemption for this rule could be a match played with a very aggressive Power-Europe-Bid). The advantage of armors is without a doubt their mobility.

Good examples for an effective use of armors:

- Russia: The ?Russian Hammer?. In this scenario Russia has placed infantry-towers in LEN and NOV and armors in MOS. So the armors menace EEU and SIN/YAK as well. Certainly a strong Russia is necessary for this strategy. If the Japanese pressure gets to high, the armors are moved to LEN and the infantries withdraw to MOS. By doing this you keep the threat on NOV/EVE/KAZ and in addition you increase the defensive power in LEN.

- Germany: Armors in Germany. On one hand they defend the capital and on the other they are available if the allies invade Spain, they menace LEN and they can support the ?Lurch? significantly.

- UK: In Asia Russia can clear Japan-held countries and afterwards UK-armors are able to attack beyond laying countries held by Japan. Even a small armor contingent in combination with air support can cause some undesirable situations for the Japanese. Especially the industrial complex in India can be endangered momentarily. Beside this, armors can be helpful at the beginning of the match to liberate Africa quickly.

- Japan: In Africa Japan can cause a lot of damage with armors. The trick is to move as many armors to Egypt as possible to force the Allies to transport more and more units to Africa. If sufficient allies? units are present in Africa the Japanese armors withdraw to Persia which will (in combination with an advancement of Japanese infantries to KAZ) increase the pressure on the allies in a way to bring down their defense.
Furthermore the use of armors shortens the lines of communication. This is very effective to bring down Russia if sufficient troops are available. Therefore you produce for one round armors exclusively, which will arrive in MOS at the same time as the infantry units built the previous round. (The same systems also works if you want to conquer NOV with Japan. By manufacturing armors you are maybe able to break the NOV-block and the additional defense reduces the chances of the allies to recapture NOV profitably. In this case you also have to consider that you will not get replenishments for one round. But this can be covered by landing air units in NOV which will increase your defense value again.)

- USA: Actually US are not in need of armors. Merely against an EGY-block of the axis armors may be helpful, but only if this forces the axis? troops to retreat from EGY.

Last but not least there is the AA-gun, which is actually also a land unit. Every time an industrial complex can be reached by an enemy bomber the IC should be guarded by an AA-gun. Thus production of new AA-guns makes only sense if new ICs are built. An exception of this rule is if the opponent has a very numerous air fleet. By having an AA-gun a forfeit is most likely not of interest anymore because of the potential threat to the attacking aircrafts.