Commanding NATO's operations in Libya, under a UN Security Council mandate for the responsibility to protect, from the end of March 2011 onwards.
There were lots of mistakes made in NATO's management of this mandate. Notably, having been given the mandate by the UNSC, a total failure to keep informed or consult with the non-NATO members of the Security Council was a basic, and foolish, diplomatic error, for which the West will pay for some time. (And indeed, Syrian civilians are paying right now: having invoked the 'responsibility to protect' and then having watched NATO turn the mandate into a campaign to overthrow Qaddafi's regime, the non-western members of the Security Council are once bitten, twice shy.) But those mistakes were made by London and Paris. Ottawa, alongside Copenhagen and Oslo, played quiet but staring roles: explicitly invoking the UNSC resolutions and the concept of R2P gave credence and relevance to NATO's air assets.
The danger ahead? Over-learning from this success. NATO couldn't have done this without the UNSC, and without Arab backing. And Syria isn't Libya.
Still, a good moment for middle power multilateralism - Canada's most effective default setting, when it remembers.