Which one is correct?
"on both fronts" or "in both fronts"?

Some examples from the web:

• My lord, we are positioned on both fronts.
• We've taken measures on both fronts already.
• The fight will come to men on both fronts.
• I believe that we need to act on both fronts.
• In the interest of time, we think it's bestto proceed on both fronts.
• Ukraine must grasp the nettle on both fronts, no matter how difficult it might seem at the moment.
• Hopefully the People's Republic of China will realize that is almost an inescapable fate unless the development takes an appropriate form on both fronts - cultural and political, as well as economic and commercial.
• Created at theoretically zero cost to reduce waste and improve the effectiveness of the European Union's external relations, it is proving to be a failure on both fronts, politically and economically.
• We have to do both and we have to move on both fronts.
• Fundamentally, I believe, we have to continue to take action on both fronts, for we must not overlook the close connection between issues of employment and social security and the question of whether we will succeed in recreating proper growth in Europe.
• So Europe must advance on both fronts: economic progress, yes, and social progress too.
• What is the current situation in this regard on both fronts (figures, Commission initiatives, etc)?
• This annual debate on progress made is, however, a gauge that specifically records the reforms that have been achieved and the mood of public opinion, and I think we can all see that there has been increasing coolness on both fronts in recent times.
• We do not have the men to face armies on both fronts.
• I fully agree with the comment made by Mr Rothley on this issue; on both fronts it is necessary for some serious adjustments are made.
• But, Master, I believe we are strong enough to engage them on both fronts.
• If you see my graph, given your motility numbers and the average amount of time it takes to complete a first adoption, moving ahead on both fronts could significantly speed up the process.
• 2011 may well prove to be a landmark year on both fronts.
• The fight will come to Men on both fronts.

Some examples from the web:

• They were probably both in that front car.
• This annual debate on progress made is, however, a gauge that specifically records the reforms that have been achieved and the mood of public opinion, and I think we can all see that there has been increasing coolness on both fronts in recent times.
• What is the current situation in this regard on both fronts (figures, Commission initiatives, etc)?
• Come with me, now, or I'll kill them both right in front of you.
• They were both killed in front of him when he was a child.
• No, they're both asleep in front of the telly.
• James does four laps, and he's in front of both ferraris.
• Out in front, both of you, where everybody can see you.
• If Dan won a physical altercation in front of both teams, there's a certain personality type that might feel impugned enough to strike back.
• I want both bikes in front, a patrol car, the SWAT truck, the ambulance and my car behind.
• Or were you just waiting to embarrass me in front of both our parents?
• Therefore, I fail to see why, in the name of religion, we should tolerate anachronistic, unhygienic and even sadistic killings of animals, sometimes done in pompous ceremonial circumstances, carried out in front of both adults and children.
• drawings, (three copies), in sufficient detail to permit identification of the type and showing the entire filament lamp on the scale of 2: 1, its shield being shown both in front view and in cross-section.
• also the filament(s) and shield(s) shall be shown on the drawings at a scale of 2: 1 both in front view and in side view;
• We do not have the men to face armies on both fronts.
• My horse's both front legs went bad.
• We've taken measures on both fronts already.
• The fight will come to Men on both fronts.
• No, position three was female superior, both front facing.
• The fight will come to men on both fronts.