It is not because you are a beginner. The problem is one of an extremely dry summer. Peas need a great deal of water to grow well and do best if sown on top of a bed of water-holding compost or manure, a little similar to runner beans for which many people supply a "runner bean trench". If this is not provided, you are reliant on the ability of the soil to retain the water with which you have presumably irrigated your peas. If the soil is lacking in humus, the water will drain away quickly or evaporate quickly and not be retained sufficiently for the peas to benefit from it. The recent spate of extremely dry summers has made growing Spring-sown peas difficult.
Unbeknown to you previously, the soils possess very different water-retaining characteristics. If the spate of very dry summers continue it will be almost "de rigour" to treat peas similar to runner beans and also spread a mulch on top of the soil to reduce evaporation.