I think you are looking for "Our army had been wearing the British Army's World War II uniform until recently."
Your verb aspect options for past tense are:
1. Our army wore - an action that happened at a point in the past
example: Our army wore the British Army's World War II uniform in the parade last week.
2. Our army was wearing - an action that was happening when another action interrupted it and the first action may have
example: Our army was still wearing the British Army's World War II uniform 25 years after the war ended.
3. Our army has worn - past action that continues now, a recent past action that is important now
example: Our army has worn the British Army's World War II uniform 10 times in their 50 year history.
4. Our army had been wearing - an action that began in the past and ended at another time in the past
example: Our army had been wearing the British Army's World War II uniform until recently.
If you want to incorporate the word "still," which emphasizes that they have been wearing the uniform for a very long time, you will need to rewrite the sentence like #2. As if you were there when it was happening.
"In 2014, our army was still wearing the British Army's World War II uniform." Note, that this sentence does not give any specific information about whether or not they wear the uniforms now. It implies that they do not, but it is unclear.
I used a reference book and these web pages to look this up: