Complex sentence: Metternich rejected the Tsar's idealistic plans for (among other things) a single European army, but his own recommendations to the Prussians for greater controls on freedom of speech proved equally hard for other powers such as Britain to support openly.
Split into simpler sentences: Metternich rejected the Tsar's idealistic plans for (among other things) a single European army. His own recommendations to the Prussians for greater controls on freedom of speech was equally hard for other powers such as Britain to support openly.