Complex sentence: Italy had declared its neutrality at the outbreak of the war but intimated, on 5 July 1914 through diplomatic channels, that Austria-Hungary's ultimatum to Serbia was aggressive and provocative.
Split into simpler sentences: Italy had declared her neutrality at the outbreak of the war. However she intimated (on 5 July 1914) through diplomatic channels that Austria-Hungary's ultimatum to Serbia was aggressive and provocative.