Can You Wipe Over Army Boots in Wudu?
Question

We are in the military and we put on sport boots for the morning training in a state of purity, then after the training ends, we take them off and put on army boots with the same Wudu as before. When we pray Dhuhr we wipe over these boots. What is the ruling on that? Does this invalidate Wudu? Is the prayer offered in this case valid?
Praise be to Allah.Is Wiping Over Army Boots Permissible in Wudu?
It is permissible to wipe over the army boots, because they come under the same ruling as the Khuff (leather socks).
Shaykh Al-Fawzan (may Allah preserve him) was asked: Is it permissible to pray in army boots? How should one do Wudu when wearing them? Is there a specific time limit for that?
He replied: It is permissible to pray in army boots – i.e., the Khuff – if it is clean and pure and there is no impurity on them.
It is permissible to wipe over them when doing Wudu if they cover the foot completely including the ankle, and are attached firmly to the foot and were put on when the person had Wudu.
The way in which wiping is done is to put the wet fingers on the ends of the toes, then bring them up to the shins.
The time for wiping over them is one day and night for one who is not travelling, and three days and nights for the one who is travelling. This is a concession which is confirmed in Mutawatir reports of the Sunnah of the Prophet (blessings and peace of Allah be upon him) and no one denies it except an innovator. That time period, according to the correct view, begins with the first time one wipes over them after putting them on. And Allah knows best. (End quote from Al-Muntaqa, 2/54)
Conditions for Wiping Over Army Boots
One of the conditions of wiping over the Khuffayn or whatever comes under the same ruling, such as army boots, is that they should have been put on when one was in a state of complete purity.
If you still had your first Wudu in which you washed your feet, and put on the army boots after taking off the sport boots, it is permissible for you to wipe over them, because it is true that you put them on when in a state of complete purity.
So you may wipe over the boots for one day and night if you are not travelling, and for three days and nights if you are travelling. The time starts from when you first wipe over them after breaking Wudu.
If you need to take off the boots, then you may wipe over the socks. In that case, it will not matter if you take off the boots or trainers, because the ruling applies only to the socks.
For more details, please see the following answers: 228222, 114192, 13954, 139719.
And Allah knows best.