The given sentences are;
'As my eldest son was bred a scholar ,I determined to send him town, where his abilitiesmight contribute to our support & his own.'
'Clivehad been only a few months in the army, when intelligence arrived that peace had been concluded between Great Britain & France.'
Which are the Main Clause & Subordinating Clause ?

Dear student,

Please find below the solution to the asked query.

1. Main clause- 'I determined to send him to town'
    Subordinate clause- 'As my eldest son was bred a scholar', 'where his abilities might contribute to our support and his own'.

2. Main clause- 'Clive had been only a few months in the army'
    Subordinate clause- 'when intelligence arrived that peace had been concluded between Great Britain and France'.

Regards