There have been some discussions going on lately about gender and sexuality in the army, particularly in the USA.
Some people seem to think that they shouldn't allow transgender people in the army. There are arguments about it being dangerous for the people serving to live and sleep among transgenders, but also about them not being strong enough both mentally and physically.
In my personal opinion, transgenders should be allowed to join the army.
As long as they pass the tests just like everyone else has, I don't see a reason for them not being able to serve for their country. Of course, they'd have to sign a form saying they agree that any medication they might be taking for their gender or sexuality might not be available when they get sent on a mission.
The most important thing when you join the army, is your will to serve. As long as you're willing to die for your country, and you're strong enough - both physically and mentally - you should be allowed to join the army. I can understand that some people might not feel comfortable sleeping with a transgender person next to them, but this is a mental barrier they have to overcome. When you're at war, you don't stop to think whether this person does or doesn't have the gender they were born with in their pants, you just think of that person as someone who has a home, a family, a life, and who wants to continue living that life.
Why would someone be disqualified just because their birth-gender is different to their current gender? It doesn't make them less of a living person.